HFC and exhaust rasp
 

Right now I have stock cats and Y-pipe, a coupe mid-pipe with a Moroso spiral race muffler in place of the stock resonator, and no muffler. Just a 2.5 pipe with a tip out the back. It sounds so good. I would like to upgrade the stock cats but I do not want to ruin the exhaust note of the car. Are all CAT upgrades going to produce a rasp in the exhaust note. I want no rasp, not even a little.

Short answer: no.
All cat upgrades will alter the exhaust note in some way, some way more than others.
High quality items like Fast Intentions is the way to go.

Any rasp you'll get w/b at WOT
 

NJ6MT, consider the fact that most of the restriction in your exhaust system is in those OE cats. Replacing them with quality HFCs like Fast Intentions will easily give you another 10 to 12 WHP. Any rasp you might get will be because of that OE y-pipe, it's like putting 2 lbs of sh!t in a1 lb can due to the extra flow...get the concept?
Gary

What he said :icon18:

i have the fast intention exhaust and HFC. you tell me what you hear.

Basically what Gary said.

To add on. If you introduce a larger diameter pipe, and then it goes back to small. This has been known to produce rasp. So if the HFC has a larger pipe diameter than the Y. You'll likely hear rasp.

Just my 2 cents.

I guess I don't get the concept. I was under the impression that the rasp comes from the natural properties of the internal combustion engine. I thought that the stock cats, as restrictive as they are, provide a first line of defense in muffling the high pitched rasp out of the exhaust note. Call me crazy but I don't think the y-pipe has anything to do with controlling the raspy-ness of the exhaust note. Am I wrong?

I don't know if you wanted me to say this but I hear a raspy exhaust note that I don't want my car to sound like.

ill take rasp for $200

JT, square your fellow jersey boy away

i just have yet to hear any chopped up stock exhaust paired with HFC or ART pipes NOT sound raspy.
I truly believe Gary is right in what he said about pairing hfc back up to stock components.

My HKS/ART pipe set up has little to no rasp- at any RPM.

So what exactly do you have?

- ART pipes
- ??? Y-pipe
- ??? midpipe
- HKS muffler?

Please keep in mind I do have a Sedan, I don't know what you have.

Buddy has a coupe so whatever he has won't apply to you

The general consensus seems to be that all HFC's produce some rasp, even with full aftermarket exhausts, but are there aftermarket HFC's that are better/worse for rasp?

http://aamcompetition.com/i-4644825-...flow-cats.html

These did me so good, they are thick and not cheap/tinny like berks. I can't speak for fast intentions though. No experience with them.

Those look impressive.