My car is making what appears to be a hissing sound, like an exhaust leak, under acceleration. The noise sounds like it coming from the front of the car. I had a bad resonator on my magnaflow and thought that might be causing the sound, but I just installed my vibrant and it is still doing it. Although you cant hear it as well because the damn vibrant is so loud. Any one else have this problem, I was told it could possibly be the Cat. I did a leak test on the exhaust and it all seemed to be sealed up tight.

 

If you haven't removed the header or downpipe then you either need to check the bolts connecting the sections of the vibrant, or replace the gasket in between the d pipe and catback. Also if there are any sections requiring bolts to hold it in place, you need a gasket for that connection.

 

I got hiss from a ram air kit...but I'm guessing it's a leak at the header to downpipe flange.

 

I am gonna check that today. I know it isnt the vibrant thats leaking because it was doing this with the magnaflow on it too, and I checked and double checked the vibrants connections. Hopefully it is just the gasket between the header and downpipe, gives me an excuse to buy one now!

 

i also had a bad resonator on my magnaflow, should have the replacement tomorrow.

is it just a hiss? an exhaust leak will also be very "farty" sounding. do you have an intake?

did you try having someone rev the car while you look around to see where it's coming from? that's what I would do if you haven't.

 

yea its a hissing sound, i thought it might be a vaccuum problem also. Im taking it up to my buddys works today and we are going to try and track it down. Are you replacing your exhaust with another magnaflow?

 

yea... i love the sound of the magnaflow. i had one on my car for about a year, then i ran over a deer and destroyed it, so i got a new one about 2 months ago.

my resonator is buzzing and vibrating, makes it sound like an exhaust leak. is that the same problem you had? if i tap it with a hammer it sounds like there's an angry beehive inside.

 

Thats exactly the problem I had, this is the third time I have had it replaced under warranty and the place I bought it doesnt carry the magnaflow any more so I got the vibrant. Im not sure if I am going to keep it cause its loud as hell, I also really liked the sound of the magnaflow.

 

yea, going from the magnaflow to the vibrant is a HUGE difference. i personally think the full vibrant setup sounds like a chainsaw.

magnaflow is the best in my opinion.

 

i had the same problem it was a crack in my cat

 

The tech at the dealer said he didnt hear anything other than normal drivetrain noise, I think im gonna have to put the stocker back on and then check it out. Was that crack in the cat noticeable while looking at it on the car?

 

no not at all... my dealer replaced it...

they didnt notice it till they took off the downpipe... They thought it was my header and it ended up just being that cat after inspection

 

keep in mind that the lsj is a VERY noisy engine, and makes some weird sounds. i've had the car for a year, and every now and then i still start the car and say to myself "what the **** is that sound"

you sure it's not the intake?

 

i agree these motors make all kinds of noises... just check the flandges and listen hard

 

i have that same noise and had my friend take a quick look and thought it might be the exhaust manifold but i took it to the shop and they said that they couldn't find anything wrong with it...so i might check it out myself when i get some time.

 

yea this is definately the noisiest car i have ever owned. Good luck, it seems that this car is full of undeterminable sounds, just when I think i have it figured out, something else pops up. It doesnt appear to be anything to worry about so thats all that matters to me. Not to mention I can barely hear it now over this Vibrant 3 inch!

 

i would check the flex joint because i started hearing that noise too, and it starts quiet but if you keep driving after a couple hundred miles it just gets worse and worse, it is probably a cracked flex joint. i had to get a new one