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      03-21-2013, 09:20 AM   #11
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Drives: F80 M3
Join Date: Jan 2008
Location: SoFla

iTrader: (3)

Originally Posted by LarThaL View Post
Stock mid pipe has secondary cats + a set of resonators. Challenge has no cats but only one set of resonators.

I was referring to simply cutting the stock secondary cats and welding resonators. This would give you a 4 resonator/no secondary cat set-up
I have had all 3 set-ups on my car with oem exhaust mod (similar sound to MPE).

First had oem mod only with factory x-pipe and it sounded awesome. Eventually, I wanted more volume so I cut out the secondary cats and replaced with straight pipes. This produced a noticeable increase in volume but also made the sound very raspy. I drove around like that for 6 months or so before getting tired of the sound. Recently I had resonators welded in where the straight pipes were for a quad resonator and no secondary cat setup. Initially I was disappointed by the reduced volume but the tone is much improved. However, not sure how different it sounds now than when I had the secondary cats in place.