Alright Cadillac Gurus, need some help, ive got an 06', 3.6 w/ 30k miles on it. Awhile back I installed a V exhaust, 2.5" as im sure you all know, im just providing as much info as possible. Last week i purchased a 2.5" magnaflow x pipe and had it installed, it sounds great, nice deep pitch, exactly the sound i was looking for EXCEPT, when accelerating at about half throttle, it makes a horrible, almost slapping sound, as if there is a nail bouncing around in the muffler. It only happens at half throttle, or between those rpms' somewhere in the range between 2500-3000. It makes it sounds like a damn rice burner because of that. Im trying to figure out, if this is natural, and if it is i will take the thing off and put the resonator back, OR is there some other known cause of this? Bad weld, air leak, etc? I am not able to get under my car, my apartment complex is much to tight to be working on my vehicle, which sucks. Im going to try to load a sound clip tonight or tomorrow, and maybe that will help. The setup is like this, removed the resonator, installed 2.5" pipe at the existing piping for about 6" till it hit the x pipe, meaning the x pipe is closer to the rear of the car, with the added piping towards the front, the xpipe is only 12" long, stock resonator is closer to 18" long. Thanks guys.