# Is the ZHP exhaust strictly a "sound" advantage??



## Tanin (Dec 21, 2001)

I have the dual 3" BB TriFlo on my 2001 330i and love it. 

Is the ZHP exhaust strictly a sound advantage? If so I will transfer my current exhaust to my 04 ZHP. 

Any thoughts?


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## Chocaine (Jul 1, 2003)

I thought the only change was that they disabled the valve that closes off one pipe at idle. Can anyone with a ZHP confirm this?

Either way, if you love the sound of the Triflo, the ZHP's exhaust just won't do it for you so transfer it.


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## mbr129 (Aug 23, 2002)

The ZHP's exhaust is my biggest complaint. I almost wish I had the regular one. Would I lose any "performance" by switching it to the stock 330i exhaust? Just curious.


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## ff (Dec 19, 2001)

I'd actually call it a sound disadvantage. The perf. pkg. exhaust masks the beautiful sound of that inline6, and that's a bad thing.


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## Plaz (Dec 19, 2001)

I think it is different... the "sport" muffler?

Just sound though. As noted, it doesn't contain the sound-suppressing vacuum-driven flap.

I don't know if any exhaust on any E46 is anything more than a sound enhancement. The only possible performance gain would be if the system was significantly lighter than stock, thereby making the car lighter, with a better HP/weight ratio. I don't think any E46 exhaust actually has an affect on engine output.


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## mbr129 (Aug 23, 2002)

Plaz said:


> I think it is different... the "sport" muffler?
> 
> Just sound though. As noted, it doesn't contain the sound-suppressing vacuum-driven flap.
> 
> I don't know if any exhaust on any E46 is anything more than a sound enhancement. The only possible performance gain would be if the system was significantly lighter than stock, thereby making the car lighter, with a better HP/weight ratio. I don't think any E46 exhaust actually has an affect on engine output.


Let me tell you, if that's the case, I seriously will consider removing this loud exhaust.


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## milski (Aug 25, 2003)

So how hard/expensive would be fitting the stock 'quiet' one?


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## mbr129 (Aug 23, 2002)

milski said:


> So how hard/expensive would be fitting the stock 'quiet' one?


Who knows. :eeps: A lot of people WANT/LIKE the louder exahust, so ideally, you could swap the exhausts and it would be a labor/install thing. I don't know if it is simple enough to do on your own, but it can't be too expensive to have it done.


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## Andy (Jul 16, 2003)

mbr129 said:


> The ZHP's exhaust is my biggest complaint. I almost wish I had the regular one. Would I lose any "performance" by switching it to the stock 330i exhaust? Just curious.


mbr129,

You may want to put your ZHP exhaust up for sale/trade on e46fanatics.com. I would bet you anything that someone will trade you straight up for their stock 330i (non ZHP) exhaust. You may even be able to get them to pay for shipping both ways. :thumbup:

Andy


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## mbr129 (Aug 23, 2002)

Thanks HACK. Didn't know that. That complicates things.

Andy: Yeah I thought of that. I am not going insane with it yet. If anything I am getting used to it. I just wish that I could hear a cleaner engine sound.


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## mys_iii (May 9, 2003)

mbr129 said:


> Thanks HACK. Didn't know that. That complicates things.
> 
> Andy: Yeah I thought of that. I am not going insane with it yet. If anything I am getting used to it. I just wish that I could hear a cleaner engine sound.


I definitely understand what you mean and it would be nice if there was such an option to quiet the exhaust without affecting the performance but I would do some good research before doing this if you decide to do it. I have some experience with exhausts and I think that most of the time, the exhaust that comes stock with a vehicle has been optimized for the car's engine/ECU and swapping that out will almost always adversely affect the HP/TQ curve. Some exhausts increase low end power and torque at the expense of throttle response and high end power. Others do just the opposite. Make sure you're getting what you think you're getting because you may dislike what you replace the stock exhaust with even more. :dunno:

Good luck. I may be in the same boat in about a month and a half when I get mine. :bigpimp:


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## Plaz (Dec 19, 2001)

mys_iii said:


> Some exhausts increase low end power and torque at the expense of throttle response and high end power. Others do just the opposite.


Presumably you're referring to some sort of correlation between back-pressure and torque, which doesn't apply to modern engines, per my understanding. UUC has an interesting little essay on the subject:

http://www.uucmotorwerks.com/html_product/sue462/backpressuretorquemyth.htm


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## mys_iii (May 9, 2003)

Plaz said:


> Presumably you're referring to some sort of correlation between back-pressure and torque, which doesn't apply to modern engines, per my understanding. UUC has an interesting little essay on the subject:
> 
> http://www.uucmotorwerks.com/html_product/sue462/backpressuretorquemyth.htm


I was partially referring to that. The real issue here is that the stock exhaust yields a particular HP and TQ curve for the car. If you change the exhaust you affect the flow of the exhaust gases and without actually doing a dyno test, you can't be 100% sure how that affects the HP/TQ curves. I've seen a few articles in European Car magazine where they did tests of multiple exhausts on a particular car and the HP/TQ curves were definitely different. Even though with most exhausts, the GENERAL shape of the curve was the same, the behaviour in certain RPM ranges were different than stock. Some reduced power in certain RPM bands so you really have to know what you're getting before you put it on your car. My personal experience is that the car's throttle response can become worse if you put on the wrong exhaust although I'm not sure why or how that would happen.


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## mbr129 (Aug 23, 2002)

mys_iii said:


> I was partially referring to that. The real issue here is that the stock exhaust yields a particular HP and TQ curve for the car. If you change the exhaust you affect the flow of the exhaust gases and without actually doing a dyno test, you can't be 100% sure how that affects the HP/TQ curves. I've seen a few articles in European Car magazine where they did tests of multiple exhausts on a particular car and the HP/TQ curves were definitely different. Even though with most exhausts, the GENERAL shape of the curve was the same, the behaviour in certain RPM ranges were different than stock. Some reduced power in certain RPM bands so you really have to know what you're getting before you put it on your car. My personal experience is that the car's throttle response can become worse if you put on the wrong exhaust although I'm not sure why or how that would happen.


I understand your concern. But valid as it may be, were are discussing potentially changing the exhaust for one which was outfitted to the same car with the same engine etc. All that has changed is the cams and ECU. Sure there could be an effect, but if there was "loss" of power it would be minimal. Likewise any variation in power/torque curves. But it goes without saying that before I take any action I would find out all I can about potential repercussions.


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## ClubSpec330i (Oct 22, 2003)

I might want to try to switch exhaust between my 330i ZHP and my wife's 330i. My wife's is '03 330i and mine is '03 330i ZHP. I do feel that my wife's car has better low end torque than my car but it could be from numerous of reasons. Exhaust might be one of them. Since my wife's 330i has been "tampered" by a head mechanic at our local BMW dealer, my uncle, I can't say how much horsepower it is putting out. 
One of this day I am going to dyno both car and compare the graph. Maybe changing the exhaust around to see whether it will improve performance or not.

cheers,


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## 31st330i (Jan 11, 2002)

The HACK said:


> Actually, it's easy to swap out, it's EXPENSIVE to get the parts. E46 exhaust is one single piece from the back of the cat, and includes both resonators. To replace the exhaust without cutting or welding you'd have to replace the entire length of the exhaust from the catalytic converters back.


I don't think you can buy the whole exuast as one piece. you buy the individual components and use the BMW clamps to hold the muffler on. works wel if you ask me.

there are at least three mufflers that I have seen available for the 330:

18 10 7 504 172 standard 330 muffler

18 10 7 504 171 standard 325 muffler (no flaper is only difference?)

18 10 0 026 767 "sports silencer" (listed for both 325 and 330)

18 10 7 919 236 ZHP rear muffler

The sports and ZHP muffles seem to be the same. Perhaps the tip style is slightly different. I also recall the sports silencer is painted gray and that the ZHP is not painted.

I believe that all three mufflers are already straight through aside from the flap on the original 330 muffler.


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## 31st330i (Jan 11, 2002)

mbr129 said:


> Who knows. :eeps: A lot of people WANT/LIKE the louder exahust, so ideally, you could swap the exhausts and it would be a labor/install thing. I don't know if it is simple enough to do on your own, but it can't be too expensive to have it done.


well, if you're local to the SF Bay Area and are willing to cut your exhaust and reinstall using the BMW clamps (I think you'd have to pay ~$50 for those), we could swap for a week or two. You'd have to make sure and cut the exhaust at the same point (which is good for at least OEM and Dinan mufflers, perhaps others like maybe Supersprint).

When Dinan designed their muffler on my car, they did it in such a way that the location where you cut off the original muffler is the same for replacing the stock muffler with another stock muffler as it is to replace the stock muffler with a Dinan. Bottom line is now that I have the clamps, I can now easily swap in and out OEM mufflers with no curring or modification. For this reason, I was thinking about ordering the sports silencer or the ZHP muffler, either of which should be a direct bolt on in my case.

18 10 1 439 722 muffler clamp (you need 2 to swap the muffler)


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## 31st330i (Jan 11, 2002)

so for ZHP people looking to quiet their vehicle down, the original 325 muffler (no flapper but you have to add chrome tips) may be the way to go. and those used mufflers might be plentiful over on phanatics.


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## Mr Paddle.Shift (Dec 19, 2001)

Am selling my 325 muffler CHEAP. Real CHEAP. Anyone interested? :dunno:


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## Jspeed (Dec 23, 2001)

ClubSpec330i said:


> ...
> Since my wife's 330i has been "tampered" by a head mechanic at our local BMW dealer, my uncle, I can't say how much horsepower it is putting out.
> ...


... and how has it been "tampered"? :eeps:


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## 31st330i (Jan 11, 2002)

Jspeed said:


> ... and how has it been "tampered"? :eeps:


yeah, good question.


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## Ashe too (Dec 22, 2001)

The ZHP exhaust may be a different diameter than the non-zhp exhaust. I've read half-a-dozen review in car magazines and they all refer to "free flowing" exhaust or similar language. I would think you would loose power by downgrading and possibly cause some odd drivability quirks as well.


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## Dr. Phil (Dec 19, 2001)

One of the lead techs at my dealer told me last night that the only difference between the ZHP and 300 regular exhaust is the sound silencing flap :dunno:


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## RandyB (Mar 4, 2003)

*Zhp...*

The cams must have softened up the low end too because even with the new diff, I have heard of complaints that the standard 330i has more low end.

I would like to have the rear diff as well... :thumbup:

I opted not to get the ZHP mainly because I love Electric Red, which wasn't available. The wheels have grown on me, but they look tough to clean and I wanted 17s for a smoother ride anyways.

I like the way my car sounds, but haven't had a chance to drive a ZHP for the sake of comparison.


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## Tanin (Dec 21, 2001)

Do I have this right?….the ZHP is heavier, noisier, has less torque, harder to shift, more difficult to clean, idles rough and cost more. 

They must have an amazing marketing program because “I” for some reason still like it. :dunno:


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## GeoMystic (Aug 21, 2002)

rumatt said:


> Wow. Seems like this is not great news for the ZHP option. The wheels possiby _reduce_ performance, and some people want the muffler to be swapped back to the original.
> 
> Except for the rear diff (which I wouldn't mind having) it's pretty much a bling-package... :thumbdwn:


Not in my eyes.

The exhaust is a bit loud in comparison to others, but not an annoying loud. I am really surprised that many of you 330i w/PerfPack owners would actually consider removing it and installing the 330i standard exhaust. What a waste!

The only differences between the two are prolly the butterfly flap and the tips. ZHP muffler tips are larger and the resonating material inside the muffler may be slightly modified.

Although the exhaust does tend to overpower the lovely engine growl to an extent, it is one of the many features that sets it apart from the other E46 sedans. I think the exhaust note and appearance compliments both the look and performance of the 330i with Performance Package. :thumbup:


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## mys_iii (May 9, 2003)

*I think that many here are most likely incorrect in saying that*

the regular 330 has more low-end torque than a ZHP. It's probably just mental like alot of things. I drove a 330 with SP and now have a ZHP and have to say that the ZHP seems to have more torque and better response all throughout the rev range. The top end is also very good as the car does not run out of breath over 4000 RPMs. If you think about it, it's very unlikely for a regular 330i to have more low-end torque. First of all, the ZHP has 8 more lb-ft of torque (214 vs 222) than a regular 330i. Second of all, due to the rear diff difference, the effective torque at the wheels is also higher for the ZHP. My guess is that the effective wheel torque curve is higher on the ZHP and it's hard to believe that an exhaust would offset that so much that the low-end torque would actually be lower. I hope that all made sense. It did to me.


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## Rich_Jenkins (Jul 12, 2003)

This discussion sounds vaguely familiar to me: I am dropping Otto off at dealership for a few things tomorrow, among them are a question on the exhaust.

I'm hearing a resonance at 2-2.5K which is louder than I would have expected and (like someone else said) seems to drown out the engine. I guess I thought I was alone in this regard; its interesting that others seem to have similar thoughts.

I don't have a problem with the volume, because I can drive my Mini Cooper S and its just as loud (or louder) and I don't have any problem. its just the particular resonant frequency on the ZHP at 2100 RPM seems to hit me right in the lower-back of my head. I find it interesting this almost all goes away with the sunroof open and the windows down.

Options right now are:

o Ignore it (wife's favorite option)
o Avoid driving at 2100 RPM (wife's other favorite option)
o Install sound deadening in trunk, floor, bottom of rear seat
o Replace with 330i stock muffler
o Replace with Aftermarket e.g. Borla, Supersprint, etc.)

So, will see what happens tomorrow. Actually I'm a little suspicious of what's going on under the car anyway since there is a odd "rattle" at the point of engagement of the clutch; no ones mentioned this but I am wondering if it might be related somehow to the resonance. So I'll be asking them to check when its on the lift for any loose connections etc...

Will update with any new data Fri...rj


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## mkh (Mar 24, 2003)

GeoMystic said:


> Not in my eyes.
> 
> The exhaust is a bit loud in comparison to others, but not an annoying loud. I am really surprised that many of you 330i w/PerfPack owners would actually consider removing it and installing the 330i standard exhaust. What a waste!
> 
> ...


This exhaust is EXACTLY what I want, both sound and appearance. So I'm one of those who is very satisfied with it. When the E46 was introduced, I complained about the exhaust being too benign and it looks too wimpy. IMO, putting a chrome tip and stupid flap in the exhaust of a performance car is just plain wrong. I was so delighted when I heard that the ZHP comes with a more aggressive exhaust that has bigger polished tips. Putting the 330i standard exhaust on the ZHP is a step backward in ergonomics and doesn't match up with the stunning appearance of the car.


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## GeoMystic (Aug 21, 2002)

mkh said:


> This exhaust is EXACTLY what I want, both sound and appearance. So I'm one of those who is very satisfied with it. When the E46 was introduced, I complained about the exhaust being too benign and it looks too wimpy. IMO, putting a chrome tip and stupid flap in the exhaust of a performance car is just plain wrong. I was so delighted when I heard that the ZHP comes with a more aggressive exhaust that has bigger polished tips. Putting the 330i standard exhaust on the ZHP is a step backward in ergonomics and doesn't match up with the stunning appearance of the car.


 :thumbup: :thumbup: 
Well said!


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## BWoodson (Oct 14, 2003)

Hey ClubSpec330i,

If you're feeling the low-end of your ZHP suffers in comparison to your wife's non-ZHP 330i, I'd guess that at least part of the difference might be the ZHP's 18-inch wheels. I'm assuming your wife has the 17's? Those are going to be maybe 3lbs or so lighter, with tires (especially the rears) being another 2-3 lbs lighter compared to the OEM ZHP 18's. Total of 20-24 lbs of rotating weight. 

I'm planning to go to 17's for autocrossing, and will lose a total of almost 50lbs (~12lbs per wheel/tire) going from the OEM 18's to light 17's (SSR Competitions). My current track car (a Maxima) loses about 20bs of rotating weight (in that case I'm going from heavy 16s to light 17s, so it's not as dramatic a difference) in track trim, and the difference off the line is VERY NOTICEABLE. The car goes from "will lay a small patch if I dump the clutch at 4k rpm" to "can lay a patch through all of first gear if I'm not careful." 

If you're facing a slow weekend, try swapping wheels with your wife and let us know what you find out!

-b./BONTRACK


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## PABS (Apr 3, 2003)

Guys..all you need to do is take the vaccuum tube that controls he flap off and plug it with anything (golf tee works well)

I can't believe people want quieter exhausts...


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## GeoMystic (Aug 21, 2002)

PABS said:


> Guys..all you need to do is take the vaccuum tube that controls he flap off and plug it with anything (golf tee works well)
> 
> I can't believe people want quieter exhausts...


  :tsk:

Performance Package exhaust does not come with a butterfly flap/valve......


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## PABS (Apr 3, 2003)

Wasn't referring to that one


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## GeoMystic (Aug 21, 2002)

PABS said:


> Wasn't referring to that one


Oops, sorry, my bad 

I also don't understand why people want to quiet down their exhaust. Especially OEM!


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## missing23 (Feb 1, 2002)

mbr129 said:


> Thanks HACK. Didn't know that. That complicates things.
> 
> Andy: Yeah I thought of that. I am not going insane with it yet. If anything I am getting used to it. I just wish that I could hear a cleaner engine sound.


Actually the exhaust 'noise' is not as bad as I thought...I thought I was going to dislike it but I don't...it just isn't that loud to me...if it does bother you just rev the darn engine higher and you WILL hear it over the exhaust!


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## Rich_Jenkins (Jul 12, 2003)

Ok, got a "NPF" from the dealer this afternoon on Otto (NPF = No problem found.)

So I guess that all is well under the car and there are no loose parts.

Ok, bear with me, but can someone answer the following questions factually:

1 - Given the ZHP option muffler was replaced with non-ZHP option muffler, would the non-ZHP option muffler have an exhaust flap? (I assume so.)
2 - Would a ZHP option car have the ECU control, vacuum solenoid and rubber tubing "already" in place to use a non-ZHP option muffler? (I doubt it.)
3 - If a non-ZHP option muffler were installed with no vacuum to drive the exhaust flap, would the flap be open or closed normally? Would the sound be quieter than a ZHP option muffler?

Why do I care? Because as someone said its not the volume but the resonance that's kind of annoying (well, annoying enough to be up on Fri night writing posts in a BMW forum) and if I could correct this, I'd just about have the perfect car...

thanks rj


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## mys_iii (May 9, 2003)

wingspan said:


> Ok, got a "NPF" from the dealer this afternoon on Otto (NPF = No problem found.)
> 
> So I guess that all is well under the car and there are no loose parts.
> 
> ...


Come on dude. Perfection is in the eye of the beholder. I know that there is some resonance around 1900 - 2200 RPM's but it's only if you apply the throttle more than 1/4 or 1/2 of the way. I usually drive between 2500-3500 RPMs anyway, especially after the car's wamed up, so I don't worry about the resonance in that RPM range. Besides, it's not good to drive between 1K-2K RPMs anyway as you lug the engine that way which results in more carbon buildup in your engine. I initially thought that the ZHP exhaust may be too loud for my tastes but the more I drive this thing, the more I love it. It's more aggressive than the usual whimpy exhaust (no offence to anyone) yet it mellows out enough after 4K RPMs that you start to hear the wonderful growl of the engine. That's perfect for me. I can hear the exhaust or the engine depending on how I choose to drive. :rofl:

I hope you get this all worked out. I, personally, would be hesitant to change the exhaust on such a wonderfully engineered machine because I believe that by doing so you may affect the low-end or most likely the high-end breathing that makes this engine just sprint to that awesome redline. 

Best wishes


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## EZ (Feb 27, 2003)

mys_iii said:


> ...I, personally, would be hesitant to change the exhaust on such a wonderfully engineered machine because I believe that by doing so you may affect the low-end or most likely the high-end breathing that makes this engine just sprint to that awesome redline.


Well said! :thumbup:


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## 31st330i (Jan 11, 2002)

...and if anyone wants to chop their ZHP muffler off, I'd like to buy it.  gotta cut it off at the right spot, though.


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## Rich_Jenkins (Jul 12, 2003)

mys_iii said:


> Come on dude. Perfection is in the eye of the beholder. I know that there is some resonance around 1900 - 2200 RPM's but it's only if you apply the throttle more than 1/4 or 1/2 of the way. I usually drive between 2500-3500 RPMs anyway, especially after the car's wamed up, so I don't worry about the resonance in that RPM range. Besides, it's not good to drive between 1K-2K RPMs anyway as you lug the engine that way which results in more carbon buildup in your engine. I initially thought that the ZHP exhaust may be too loud for my tastes but the more I drive this thing, the more I love it. It's more aggressive than the usual whimpy exhaust (no offence to anyone) yet it mellows out enough after 4K RPMs that you start to hear the wonderful growl of the engine. That's perfect for me. I can hear the exhaust or the engine depending on how I choose to drive. :rofl:
> 
> I hope you get this all worked out. I, personally, would be hesitant to change the exhaust on such a wonderfully engineered machine because I believe that by doing so you may affect the low-end or most likely the high-end breathing that makes this engine just sprint to that awesome redline.
> 
> Best wishes


Point taken. Today for instance I just basically let the engine hang out (just got past 1200 miles, so no more RPM limiter). I never got it out of 4th, even though I was up to 60+ MPH at times. Engine seems louder (duh), but smoother and no drone between 4-5K RPM.

So, maybe its just a matter of me adjusting (remember I'm coming from 5 years pushing a MBZ C class around) to a bimmer, in particular THIS bimmer.

On the exhaust, I was asking about replacement in a more academic manner, rather than really starting to get the cutting torch out and rip out the exhaust.

I am going to just drive the nuts off the car and enjoy it...after all I picked the Performance Package, not the LeSabre Package 

Thanks for the thoughts...rj


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## russcoop3 (Dec 9, 2017)

31st330i said:


> ...and if anyone wants to chop their ZHP muffler off, I'd like to buy it.  gotta cut it off at the right spot, though.


I think I have last work on 330i vs 330i ZHP mufflers. 330i coupe 330xi have vacuum baffle up to 2500rpm
same part number as ZHP for muffler alone, what they weld to the back is different, 330xi get valve and smaller 
diameter discharge end tips. ZHP gets full quarter inch large exhaust tips, same muffler, dip in chrome, not fancy stuff,


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