possible exhaust sound from muffler

[2002blackz28]

I had a borla cat back exhaust put on my car and also have higher flow cats installed. I notice a swoosh sound of some sort coming from under the car or mabey the back by the exhaust when my car shifts into second gear. I just had the tranny rebuilt but I can't pinpoint the sound..Does anyone know what the sound could be coming from. Oh ya the sound was there before the tranny rebuild

[0rion]

I would say with 100% certainty that there's an exhaust sound coming from your muffler. Can you describe the noise any better? Could just be normal with free flowing exhaust but I really don't know what you're trying to describe. Are you running open plates in the borla? Checked for leaks?

[2002blackz28]

Sorry LOL, yes I have the borla with the adjustable plate system . It sound like a brief swoosh at the moment It shifts . Its not high pitched or anything or does'nt sound like grinding of any sort. My first thought that the clutch is slipping alittle. But I just had the tranny rebuilt .I just thought that someone else out there has this same sort of sound also..Its shifts find at any speed either downs shifts or up shifts under light or WOT. Goes right into gear and takes off quick. 2002 z28 A4 75,000 miles.. Thanks for responding. Please advise before I take it back to the tranny place and the guy there makes me look like an IDIOT.

I ran it today with the biggest opening plate installed Pretty much bypassing the muffler and its real noticable . I just took switched the plate over to full block off so all of the airflow is going threw the muffler. THe sound seems to have been cut down at least in half.This is my first z28 I've ever had .And the first car that i've had with aftermarket exhaust.

[0rion]

Sorry LOL, yes I have the borla with the adjustable plate system . It sound like a brief swoosh at the moment It shifts . Its not high pitched or anything or does'nt sound like grinding of any sort. My first thought that the clutch is slipping alittle. But I just had the tranny rebuilt .I just thought that someone else out there has this same sort of sound also..Its shifts find at any speed either downs shifts or up shifts under light or WOT. Goes right into gear and takes off quick. 2002 z28 A4 75,000 miles.. Thanks for responding. Please advise before I take it back to the tranny place and the guy there makes me look like an IDIOT.

I ran it today with the biggest opening plate installed Pretty much bypassing the muffler and its real noticable . I just took switched the plate over to full block off so all of the airflow is going threw the muffler. THe sound seems to have been cut down at least in half.This is my first z28 I've ever had .And the first car that i've had with aftermarket exhaust.

the fact that putting the plate in cut the sound in half would make me think you're probably just hearing the exhaust itself when the rpm's drop suddenly at the shift. I'd have to hear it in person to get you any closer than that but it really sounds like that's all it is and it's normal. Any gearheads local to you that you could take for a ride and get their opinion?

[2002blackz28]

I talke with a couple guy's today and they think its the exhaust .I will take it to a couple of local garages friday and get there opinion.Thanks for the info. I wil post back friday night. I guess another option would be to strap myself to the rear deck and let my buddies take it for a spin and listen for the sound ....LOL

[0rion]

I talke with a couple guy's today and they think its the exhaust .I will take it to a couple of local garages friday and get there opinion.Thanks for the info. I wil post back friday night. I guess another option would be to strap myself to the rear deck and let my buddies take it for a spin and listen for the sound ....LOL

the proper way to do that is with a skateboard and bungee cord.

[2002blackz28]

the fact that putting the plate in cut the sound in half would make me think you're probably just hearing the exhaust itself when the rpm's drop suddenly at the shift. I'd have to hear it in person to get you any closer than that but it really sounds like that's all it is and it's normal. Any gearheads local to you that you could take for a ride and get their opinion?

Well I finally got to the bottom of the problem. It was somthing in the tranny. Not enough pressure or somthing.

I just receive my DiabloSport U7198 -Predator Flash Programmer this moring and Installed the Diablo tune that it came in and no more swoosh sound when shifting just the cool sound the Borla exhaust makes like normal. It also shift quicker and with more authority. I even adjusted them a little firmer over the tune that it came with. Now all my shifts are quick and aggressive with no swoosh sound It chirps them going into second gear also.

Did the tranny guy not adjust somthing correctly. And will the tunes that I put in it hurt anything. Please let me know what would cause the swoosh sound problem I had before the tune,