I6? V8? V12? Can’t tell which set-up by the pic alone.

If I just pick a model/model year out of the blue (pre LCI f01 750i) and go to the exhaust diagrams...the bushing clamps in the illustration have their diameter listed in the part number index below the diagrams. Perhaps this could work for your application as to whichever model you have. I’m not sure if all models use the same exhaust pipe sizes.

For example, the clamping bush in the diagram below for the pre LCI 750i rear exhaust ( #2) is listed as having a 70mm diameter in the part database:

...the clamping bush (#5) for the pre LCI 750i center exhaust is also listed as 70mm:

...and the same goes for the front silencer for the pre LCI 750i...the diameter of the clamping bush (#8) is also listed as 70mm:

 

2010 750Lix. Thanks, QSilver! I'll double check, but mroe than likely it's going to be 70mm.