Originally Posted by Tractionless (Post 4052423)

I developed the hiss which sounds like quick metallic rapping imo like a leaking exhaust gasket, immediately upon installing high flow cats. I brought it to my exhaust guy to verify none of the gaskets were leaking, they were not. Luckily mine only happens for a couple hundred rpms around 2000 rpm during decel.

From what I've read ,it culminates from the headers/cat area where the sound is actually produced and heard so it doesn't matter what else you have installed downstream as the sound is not coming from the tail pipe(s). Seems to be exhaust pulses hitting the exhaust piping walls in the component bolted the the header.

Originally Posted by Averying (Post 4052425)

Yep sounds about right. Seems like ART pipes help with the resonance chambers. Haven’t yet looked to see if it still occurs with long tubes but I imagine so.


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Originally Posted by Tractionless (Post 4052558)

Would be an interesting poll to start to see what exhaust components produce the hiss. Mine are FI resonated high flow cats bolted to OE exhaust manifolds. Wonder if the long and short tube owners experience the same. :confused:

Originally Posted by Rusty (Post 4052568)

FI LTH's, 12" resonators, FI cat back. I get the hiss every once in a while.