Posted by David B on July 01, 2001 at 01:23:49:
In Reply to: Exhaust Saga / Questions / Plan / Comments please posted by Troy Rudolph on June 29, 2001 at 23:05:28:
You're right that the mass doesn't change but there is a change (loss) of volumn with combustion. I have found that it's very hard to improve on factory parts. Dinan modifys factory M3 mufflers because they can't build the same quality part at a resonable cost. If you're running a cat. the stock USA resonator and mufflers are made out of a low grade stainless steel. This is to resist the acids generated as a byproduce of the cat. The 3.5 resonator sounds like a good start but if this is a euro part it may not last long. My euro 323i was rotting rear mufflers every year and a half after I installed a cat. for smog testing. Leaving the second muffler out should reduce back pressure and give a more "sporting" sound with out being too loud. The 635 rear muffler now leaves you with a stock system. Maybe too quiet. If you want more flow I would modify the rear muffler and not the resonator. Interested to hear what you end up running.