Im thinking this could be a common problem with the 3.1's b/c ive heard other cars having a simular sounding exhaust. Anyway, on to the subject. Basically, my Grand Prix 2 door 3.1 runs good, but sounds terrible. The exhaust sounds like a run down 4 cylinder. lol...its just annoying. When the car is sitting still and idleing you can hear a flutter of the exhuast..but it sounds like it is comming more towards the engine bay area than in the mid/back portions of the car. When you accelerate the noise (obviously) becomes louder.
To make it weirder there has been (a few) times after driving the car for a little while, that after stopping, i can rev the engine (in nuetral) and it sounds as smooth as can be (or at least not nearly as bad). But sure enough it always makes the noise next time i drive it.
Also..im pretty sure my EGR valve is bad in the car b/c the check engine light comes on at times and the code points to the EGR...(havent replaced it cause i was told its not necissary and that EGR valve is an emmisions thing only) Could this cause some of the noise? I dont think the EGR is the whole problem cause it has been making this noise way before my check engine light for the EGR came on.
Maybe this whole question in general is dumb but im just curious..any suggestions? thanx people. :smile:

IF the EGR is stuck shut, the gasket that seals it may have blown out and is leaking. I would also check for a manifold to pipe flange loose or a bad gasket there. The EGR is MUCH more than just an emissions thing, without it the engine can run dangerously lean and cause severe engine damage down the line due to excessive cylinder pressure and knock. Get that EGR replaced, and all your problems may disappear.