Hissing from h-pipe with cats??

[5oh4fun]

Well, I just installed a high flow h-pipe with cats and now it is making this hissing sound at WOT and under load. It kinda sounds like a fender CAI sucking in air. It is constant and doesn't have a pulsating sound like an exhaust leak. Could this be from the pipe leading to the smog pump? If so will this damage the the cats? Could this be normal? I've never heard this sound before. Thanks, any help appreciated.

 

[UVBNHAD]

Hop down after you drive it for a while and see if your cats are red; which would indicate extreme heat and what not. It may be that you smog pump is screwed up and you are burning your cats up.

 

[HISSIN50]

oops, i thought i heard my name.




i might check vac at steady 3K or so - see if while you keep the revs the same, the vac drops. that suggests an exhaust restriction.

good luck.

 

[Daggar]

Hop down after you drive it for a while and see if your cats are red; which would indicate extreme heat and what not. It may be that you smog pump is screwed up and you are burning your cats up.

It's very unlikely that this would happen due to a smog pump problem. Foxes are not so dependant on the smog pump. I've run many many miles with the smog pump short belted with no problems (although the pump did sieze once after an extended period of not turning).