[John in Norcal]

I recently put some modified 3.4L mufflers from my old 99 6spd 996 on my current 01 Tip for better sound. I liked the improved exhaust note but the car developed an unwanted vibration when stopped and in gear (D or R). There is no vibration when the car is moving or when the transmission is in 'P' or 'N'. Yesterday I put the stock 01 Tip mufflers back on and the vibration went away. I checked and learned that mufflers for 3.4L 6spd and Tip cars have different part numbers. Visually, the only difference I could see on the mufflers is that my stock 01 Tip mufflers have the accordian inlet pipes while the 99 6spd mufflers have smooth inlet pipes. I'm not sure if this difference has anything to do with the vibration.

Anyway, I'm still looking to upgrade to an exhaust with more aggressive sound but am concerned now that if I put aftermarket mufflers on my car the annoying vibration will come back. I would like to hear from other 996 Tiptronic owners who are running aftermarket exhausts: Do you have any vibration in the car when the car is stopped and in gear? If not, which brand of aftermarket mufflers do you have on the car? Thanks for any helpful input.