Butt dyno said the engine noticably breaths better. Im not saying it gained massive amounts of power, but it seems to "glide" on acceleration moreso than before. Like it wants to accelerate easier. I also have done some headwork and opened up the stock airbox which is restrictive (diy dinan box basically) and the exhaust was one of the last major "restrictions".
Originally Posted by Iceman00
Any power/torque gains on the "trusty" butt dyno? How does it sound?
Soundwise i've been complimented many times on it. Completely random people saying it sounds awesome. The rear muffler is a Mac flowpath - you see them a lot on mustangs. Same idea as a flowmaster but sounds a LOT better-not the "hollow" sound. I used it because I have a set on my big block v8 and love the sound-its a nice deep tone. It makes the bmw sound even better-not a super high tinny sound but a good growl.
I have a video of the exhaust on youtube, but honestly it kind of sucks. car was cold and I only revved it to about 3k. I need to find someone to record a video of a driveby since apparantly thats where its zexxy time. youtube is blocked here at work so i cant find/post the link.
Only bad thing is there is a NASTY drone around 2500-3000 while partway on the throttle (i.e. highway)-but you generally get this with any car and any engine size with a 3" exhaust. It has to do with the exhaust harmonics and pipe size. For some reason 3" tubes like to resonate at 130-140hz. However, in a couple weeks I'm going to add something to the exhaust that should hopefully eliminate that. That's really the only complaint.
If anyone's in the DC area I'll bring it out one day so people can hear it/ maybe get a recording.
Last edited by NightRunner; 05-12-2009 at 07:28 AM.