[Warp Ten]

Well after thinking about (and pricing) the MPPSK I decided to just go with the M Performance exhaust. Had it installed last week, about $2,100 total, including labor and all three parts as noted above (muffler, tips and rear valance). My impression so far is that it is definitely louder than stock and under strong throttle in Sport Plus sounds excellent, and manual shifting makes it sound even better. However, contrary to several opinions here, I find it has noticeable resonance (drone) at around 2,200-2,400 rpm under light to moderate throttle load. Especially noticeable when the transmission shifts up and the revs land in that zone at the upshift. I am particularly aware of this as for about 20 years I did a lot of research and testing on resonance in C4 ZR-1 exhaust systems. The ZR-1's LT5 engine had two specific resonance peaks, one at 1,800 and one at 3,400 rpms most noticeable under medium to light load. I have not driven enough yet to see if the B58 BMW engine has two noticeable resonance peak points but will eventually. Fairly common for engines to have two. I find that to minimize it (like with my wife in the car, lest she notice that I actually spent the money on a new exhaust), I can drive in Comfort with a light throttle and keep it under 2,400. Passed the test with her in the car last night. I notice that when idling in Comfort it has slightly softer sound than when idling in Sport, so there must be a valve involved somewhere. Anyway I will continue to enjoy it and see if I can find a solution to this. I suspect not, as taming a resonance peak usually requires something called a Helmholtz Resonator, a chamber ordinarily encased inside a muffler or center resonator. We'll see. I kept the takeoff parts just in case it becomes too much, but otherwise enjoying it so far. --Bob