I just instaled my pettit dp. Should it make my car louder? It seems louder at the dp. Could this be a leaking gasket? I hope you people tell me that it is normal, because its a hollowed out 3" pipe. Everything went together perfect. Also my car is idleing kinda bad (it almost dies, when I come to a stop)
Oh yeah when I first stated it up for the first time, I thought the f***ing thing was on fire! It smoked like a mother F., but it just burned off the paint or something.

 

How much louder is it? Mine increased noticeably, but it's not that much louder. I think if you had an exhaust leak at the manifold -> DP it would not only sound much louder, but it would also tick a little. The idle might be a vacuum leak, what did you remove to do the install? Check your 02 sensor too.