Raspy Exhaust (no cats), need advice

[jmatta]

Have you considered high flow cats? My guess is you've actually decreased power because of the lower back pressure. The engine wasn't designed to run without cats. How do you get around the dreaded CEL or do you chose to ignore it?

[Boxtaboy]

I don't think the raspiness will go away by changing your muffler. I have heard a 2000 Boxster S with bypass pipes, and a PSE, and it still had some raspiness even though the 2000 model yr. had a set of pre-cats on the headers. I know you don't want to hear this, but to get rid of the raspy sound, you'll probably have to put the cats back on or get sport cats, and then a throatier exhaust to attain the sound you want.

Or, you can get sport headers, put the cats back on, and you'll also yield a throatier sound without the rasp.

[releese78]

High flow cats may be something to consider. I got around the CEL by using spark plug de-foulers to pull the second set of O2's out of the stream a little, this works great.

It doesn't seem like I lost any power, if not a little more gain at higher rpm's, but slightly less bottom end torque (barely noticeable).

[Dragonwind]

I'm going through the same thing with my 99. I put high flow cats on and it sounds exactly as you described till it gets to full temp, then it isn't as bad. I've pretty much determined that I need to go back to stock but I need a replacement OEM cat first as one had the o2 threads destroied.
Chris

[986rgt]

How many miles on the hi flo cats? I might be willing to trade you. I have factory cats, but would love hi flo ones for my setup.

Steve

[jaykay]

Has anyone done the Crios mod and bypass pipes? I would think that this might give a deeper sound on an S at least (main cats are in the headers.

I was going to do this but really do not want the er....em dare I say ricer tone..

I am after a deeper flat six grunt...

[Cloudsurfer]

Originally Posted by jaykay

Has anyone done the Crios mod and bypass pipes? I would think that this might give a deeper sound on an S at least (main cats are in the headers.

I was going to do this but really do not want the er....em dare I say ricer tone..

I am after a deeper flat six grunt...

Only the 2.5 cars have one set of cats, any 2.7 or 3.2 has 2 pre-cats in the header, and two secondary cats in the mid pipe.

[Dragonwind]

Originally Posted by 986rgt

How many miles on the hi flo cats? I might be willing to trade you. I have factory cats, but would love hi flo ones for my setup.

Steve

PM sent. Thanks,
Chris

[Gent]

If you are hearing rattle noises, I think an earlier poster was correct - your old mufflers are more likely the source of the offensive noise. Old cats and old mufflers can start to come apart internally producing all kinds of rpm dependant noise.