my car starting hissing super loud. From inside it almost sounded like an air leak in my firewall or something.
When i got back home i put a jack under the car and found the flange that bolts the cat to the resonator broke off and was leaking exhaust pretty bad. It was a pretty good size leak.


Here are the goods.
Car is idling fine.(Not rough/missing or at abnormal rpm and sounds good)
No smoke from anywhere
No strange smells
No check engine lights
Car seems to be boosting but slightly slower.
Still a loud supercharger whine

The bads.
Distinctive exhaust leak sounds from under the car
very loud hissing noise under acceleration from the air filter
Car has lost power. Not all, but some. Seems like just a couple psi

Here is a video of the sounds


I am wondering if this hissing noise is from the exhaust leak.
It kind of sounds like a scuba diver breathing from his air tank

 

Did the flange break or just the gasket between them? Can't really see where anything broke. I do see the gap there though.

 

Sounds like you know the cause, the effect and the fix....
usually when a repair like this is done, a new gasket is needed...they harden, and will leak if reused.
The flange may or may not be good on either pipe...depends on the amount of corrosion.

PS...you meant to say...er..track right?!

 

Do you want us to be impressed that you went 140 or feel sorry for you because you haven't figured out that the gasket is leaking?

 

He just forgot to mention that he was at his 2nd home in "Mexico"

 

Ibtl

 

Looking at the flanges and the bolts, someone worked there before... Flanges aren't straight and those bolts aren't oem (as well as the black on the back of the flange where it was heated up to remove the stock studs/nuts). New gasket, bolts nuts and get that flange straight, voilà, no more leak.