UCSB-S2K

Hi Guys,

Those of you with experience with HKS exhausts: After my AP1 warms up or after a drive the sound changes on my HKS exhaust. When cold its that great grumbly sound signature of the exhaust. But after the car warms up or a drive on the freeway the sound changes to a single tone, louder drone. Not cool. Has anyone else experienced this? Is it because the cat is warmed up and changing the flow of the exhaust? Will a Berk High Flow Cat fix this problem?

This issue has been frustrating me and I'm considering the Berk HFC or going back to stock.

Thanks for your help guys!
UCSB-S2K

Golem

No expert here, but from what I have experienced and what I have read on the forums.

I think every exhaust has a cold start sound and a warmed up sound.

The spoon on my AP1 is the exact same way. Except I wouldn't know why yours sounds better when cold as compared to warm/hot

kaansahbaz

We gotta hear to tell if it sounds right or not. it might be the right sound that your talking about. infact i like the hks warm engine/exhaust vtec sound

UCSB-S2K

The sound change is very drastic. Cold: typical HKS exhaust sound, like in all youtube clips, grumbly, throaty, high end sounding note, awesome, similar to a nissan v6. Warm: constant single tone, fart can-like, drone, louder, similar to most single exhausts out there.

It's like a night and day difference. You would think I put on a different exhaust if you heard the difference.

Ideas?

kaansahbaz

canister might be done, i mean exhaust might be broken inside and might do the problem when the metal is warm and gets softer (my idea)

rydelow

i had the hks. same thing happened to me. got rid of it cus of the drone and robbed the car of power. my dyno proves it lol

UCSB-S2K

Yo rydelow,

How long did you have the exhaust before that started happening? Good to know. More leaning going back to stock with that 411. Thanks!

jerZs2k

Thats pretty normal. And if you get an HFC it may gett louder. I have an MR single exhaust. It sound crappy at cold start. But has a nice tone when warmed and on freeway.

tkeyyy

my exhaust is a lot louder when it's warm, but it pops when it's cold

whiteflash

Every exhaust should have a much different sound at cold start than when warm... it's called science