New exhaust but weird fart noise when it shifts?

[ryeguy666]

Hello all it has been a while, I just got a new exhaust system on my 03 Pt GT auto stick. The local shop took a 2.5" pipe exspanded it to 3" to make a down pipe (about foot) then the 2.5 pipe runs stright back to a magnaflow(all one piece). Sound great rumbbles when you hit the gas and pretty quite while crusing. I did notice when i jump hard on the gas in first gear when it shifts to second i get a really weird fartty kinda back fire noise not so bad 2nd-3rd gear but still there? Also noticed a little back smoke stain under the bumper (white paint). Just wondering if i have enough back pressure, but with a turbo do i need any back pressure? Dont want to do any long term damage, LOVE this CAR!!

[Mean Green]

Originally Posted by ryeguy666

Hello all it has been a while, I just got a new exhaust system on my 03 Pt GT auto stick. The local shop took a 2.5" pipe exspanded it to 3" to make a down pipe (about foot) then the 2.5 pipe runs stright back to a magnaflow(all one piece). Sound great rumbbles when you hit the gas and pretty quite while crusing. I did notice when i jump hard on the gas in first gear when it shifts to second i get a really weird fartty kinda back fire noise not so bad 2nd-3rd gear but still there? Also noticed a little back smoke stain under the bumper (white paint). Just wondering if i have enough back pressure, but with a turbo do i need any back pressure? Dont want to do any long term damage, LOVE this CAR!!

A turbo LOVES no back pressure. The noise you are describing is quite normal. You ought to hear the noises my exhaust makes on my SRT-4. I have a 3" o2 housing, 3" DP w/high flow Magnaflow cat and the Mopar 2.5" exhaust w/bottleneck removed. A SRT-4 has no mufflers and my Mopar exhaust came with just an 18" resonator. My wife can hear me 2 blocks away if I really get on it.

[bobs turbo pt]

"My wife can hear me 2 blocks away if I really get on it."

that is the best !!

[slartyblarfast]

What your hearing is the computer shutting off injectors when the transmission shifts. It does that to make the shift smoother. That along with a muffler that is probably pretty much a straight thru design magnifies the sound. I used to get the same thing with a Lincoln i had that glasspacks on it. It would fart when the engine was turned off. I've had 3 PT'2 with manual transmissions and when you coast for a little bit the PCM shuts off the injectors to try to save fuel. It would actually be louder than when the engine was running sometimes. My 06 GT sounds really good when it does it.....

[ryeguy666]

Thank You all for the info just wanted to make sure I wasnt headding down a bad road. About to Add a Stage 1 here in a month or so. And im sure I will have more Questions.