Rasp will be 10 times worse with HFC's if the OEM cats cant stop it.

Heres a link to how my exhaust sounds at the moment. This is with Momentum headers, 350z stock OEM cats, and CNT exhaust. I know I'll have quite a bit of rasp once the test pipes go on.

370z Rev up - YouTube

:iagree:

I think they are hearing the headers too...
If the headers aren't wrapped to hell, Stillen headers make a tinny noise

Hfc's don't cause hardly any rasp if any. Remember, they still have a core in them, just not as large and more free flowing than stock cats. TPs are going to give you a ton of rasp depending on exhaust you have. I'm going to wrap my TPs and add smaller resonators on my Ark exhaust to get rid of some of it.

i had stillen hfc's and mine rasped quite a bit.......

You sure you aren't getting rasp and hiss mixed up. Because with hfc's you will get that hissing noise. And if you think you are getting rasp from your stillen cats than you are gonna love your tp's. Lol

I have the same headers you have with an Ark exhaust and TP's and it is ungodly loud and rasp like crazy.

100% sure it was rasp and dont worry, im ready for worse lol. I got the resonated test pipes on the way but we both know it wont do much lol. rasp and the noise dont bother me much. I mean hell, its a racecar right? :stirthepot: the ark is a more loud exhaust but gawd i love the ark exhaust.... wish i stuck with my gut and went that route lol. but now F.I. is in the works lol.

The M370 manifold will help with rasp believe it or not, not sure how, but it cleaned up my exhaust note. Having 18" resonators and exhaust cans will help too. I was worried with mine, but it was 99% gone after the intake manifold was installed. For kicks, I ordered a resonator for my Y pipe to play with too.

These issues have persuaded me to look into the 18 vs 12 resonators..probably will end up getting hfc and more at some point, try to keep the decibels down. :)

thats actually very exciting to hear! Ill be optioning for the 18" resonators when i order my F.I. exhaust but im quite intrigued on how the manifold reduces rasp.....engineers chime in please!

Have no idea why lol, It may have changed the velocity of the exhaust because longer intake runners? Regardless, it was the first thing I noticed when I reinstalled my stock manifold. I was butt hurt because it came back and did not sound as nice haha. Inadvertent benefit.18" resonators will give the TP's and headers a nice balance. I understand people like loud, it will be loud and aggressive without being obnoxious. MY Tanabe exhaust was rated at 93db though... pretty quiet when I'm not on the throttle. The second I tip in the gas, it opens up a serious can. I couldn't imagine LTH's/TP's with 12" or no resonators at all. I would purchase an insurance policy on my ear drums.

:icon18:

Lol another one of these threads? Well I'll chip in then. I'm running:
Stillen Gen 3 CAI
FI LTH
FI CBE non res'd w/ CF mufflers
Stillen lightweight pulley
Uprev tuned

Not really any rasp (and by rasp I mean the sound of a rusty civic that's powered by an angry swarm of beezzzzzzzz) although it is pretty loud. When I go to work in the morning my exhaust rattles the pictures on the walls of my neighbors house. Luckily they love my car and don't care, I've become their alarm clock lol.




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