I am hearing a low pitched BUP BUP BUP while my car idles, it increases in frequencey once the car warms up? I hear it most in the engine bay but also from the rear. Is this a problem? The sound kinda reminds me of the backfire i hear when downshifting sometimes. Any thoughts would be appreciated.

 

mine does that too! maybe its one of my problems:

broken BAC
gutted cats (temp until racing beat system comes)
timing off?

i unno, im just gonna live with it till i microtech
woot!

 

Well i have straight pipes so it cant be the cats, maybe the timing ill get it tuned once its registered.