Need your help...I've had my STILLEN CB exhaust and Gen 3 intakes for about 3 years now. I've been very happy with the sound and performance so this past week I decided to complete the package by adding their HFC in order to gain some more power and a lil more sound. After installing the HFC there was a pretty nasty (not in a good way) raspy/rattling sound. Thinking it was perhaps the HFC (the exhaust was not making the noise before), the car was put back on the lift and checked for leaks- nothing. After revving up the engine we noticed the sound was definitely coming from the Y-Pipe (as a precaution, the Y-pipe was removed to check for debris and nothing was found).

The shop mechanic suggested deleting the Y-Pipe and custom building some pipes to convert the unit into a real dual-pipe exhaust. This is where you guys can hopefully chime in and answer my questions :

1) Would deleting the Y-Pipe definitely eliminate the rasp? Has anybody tried this?

2) Could deleting the Y-pipe make some cell or or other light come on?

3) I am assuming performance would be improved due to the improved flow...is this correct?

Looking forward to getting rid of this nasty sound (buying another exhaust is not an option).

Thanks in advance!

 

Lemme guess, it wasn't there with the stock cats, but it started after install of the HFC. Sounds like a rattlesnake kinda. Can't hear it when accelerating, but is very prevalent on rpm drop(decelerating) from 2400-1800....right?

It's called the VQ hiss.

Sucks, and there's nothing you can do about it (least what I've been told). Something to do with our engines and the way they're designed. I've found out that its louder when the exhaust is cold, but after a while of driving it softened a little...but you can still hear it.

Can't hear it with oem cats, a little louder with RHFC, louder with HFC, loudest with TP....again, what I've been told.

Only thing you can do if you don't like it, is to put the oem cats back on.


Again, this is what I have been told, and i am in no way a mechanic so I have to believe what has been told to me until someone proves otherwise.

 

Hey man,

Thanks for the reply. It's pretty much the same noise that a pipe hitting against a heat shield would make, only it's audible at all RPMs (while revving up, accelerating, AND decelerating). I can even hear it bouncing off the sidewalks when accelerating at low speeds with windows down- it's a raspy, metallic, rattly sound . I'll try to upload a video to show what I'm talking about and then you can tell me if it's the hiss you are referring to.

 

here are a couple of videos with my berk HFC 2nd video you can hear ths hiss sound..

 

Thanks. I didn't really hear any hiss noise on your videos. I took one of the car parked where you can really hear it by just revving up a little. While driving it sounds the same but louder and with some rasp to it.

I didn't make the video public so here is the link:

Stillen Exhaust and HFC Rasp - YouTube

 

that rasp you hear is normal...that's the HFC sound..

 

OK. Any thoughts on eliminating the Y-Pipe as a means of eliminating the rasp?

 

deleting the Y-pipe and make it a true dual will actually increase the rasp.
as for perofrmance, i think it wud make u lose some power ( probably u won't feel it ).
true dual = more flow = less scavenging = less power.

i wud recommend you to leave it as it is