Quote:
Originally Posted by m3alabama
I actually had the chance to drive a friend's car with the ACM mod done and I can say it definetly has no rasp if that is a concern. I have heard the m performance both outside and inside and now the ACM outside and inside and you would have to be a total audiofile to recognize the difference.
With that said the ACM mod definetly does give you some drone at specific RPM's which is 75mph-85 mph in 7th gear. At 70mph and below it is ZERO drone.
So for the majority of people who cruise the highway and stay at 70mph cruising than this gives you the M performance exhaust for 300 bucks (minus the cool tips).
For those set on driving at 75 or above consistently and want zero drone than the M performance is better in that respect.
I forget which thread it was on but the M performance is simply a straight through design very similar to the ACM with some extra piping shooting off the side to control drone but the two sides of the muffler are not connected by any pipe like the OEM so its 2 straight through mufflers as well.
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If you look at the picture of the M Performance on EAS website you can see a pipe connecting left and right. I don't think it's there just for the look. I could be wrong.
http://www.europeanautosource.com/pr...exhaust-e9x-m3