tasilver

iTrader: (2)

I have noticed that under heavy acceleration between 4500 and 5500 rpm I hear noise that sounds like pebbles or little rocks flying through my exhaust. I have new kooks headers (coated) and X-pipe with cats. I also had a new LS7 clutch, custom cam, and valve train installed. I have just noticed this in last day or so.

Any ideas ?????

crazyelf

iTrader: (21)

I think headers seem to amplify valvetrain noise. With the combo of new headers and an aftermarket valvetrain(which is almost always noisier than stock) I would say its probably normal. But im no expert lol

Darkman

iTrader: (2)

I have heard of failed cats sounding like that, but it usually involved OEM cats with a lot of miles on them.

Michael02hawk

iTrader: (26)

Most likely, its pinging from too much timing.

Was the car properly dynotuned after the header install?

RevGTO

iTrader: (12)

If you have ceramic core cats, there's a good chance one may have (partially) disintegrated. That's what it sounds like. Happened to me a few weeks after I smacked one on a high spot.

tasilver

iTrader: (2)

Thanks guys I will check and see what type of cats they are. I had the car dyno tuned at VASpeed and know the tune is good. I think it may be the cats even though they are brand new. I know that every manufactured product is subject to some defective so I hope it is the cats.