Strange hissing

[AngryHippo]

Hi everyone, having an issue with my 04 z at the moment. I currently have HFCs, plenum spacer and scorpion exhaust fitted. I have been running berk HFCs for around 4 months now and have gotten used to the usual hfc hissing noise upon releasing the accelerator after booting it a bit, but I have started to get a different toned raspy/hissing noise at around 2-3k revs, upon accelerating. When I release the accelerator I get the odd sounding hissing/rasp before I get the normal rasp sound of the HFCs that I am used to hearing.

 

I am not really sure what this could be that is causing it. My y-pipe is stock and looks like it needs to be replaced. The bits that sort of bulge out on the y-pipe, that look like are wrapped in a metal sheeting (not sure what they are called) look pretty buggered, looks like the metal sheeting has been burnt away a bit. Hopefully you can picture what I mean. I don't know whether this would be a cause, maybe a leak of air, or vibration of the frayed metal sheeting making the weird raspy noise?! Any help or advice would be greatly appreciated.

 

One further question, would a y-pipe such as japspeed or stillen help improve air flow/increase performance over stock with the settup I have currently got?

 

Thanks in advance

 

Jay

[MITZ@CougarStore]

Jay, the Cobra Sport Y pipe we do would marry up perfectly with the rest of your exhaust, it can be seen here - http://cougarstore.co.uk/index.php?main ... cts_id=126

[DannyBoy]

The usual HFC noise is the one that you seem to be describing as new and strange; the rasp at about 3k rpm. The hiss when you let off the throttle I have never heard of before, and my HFCs certainly don't do it. You sure you don't have a turbo?

 

You definitely want to get rid of the stock Y-pipe, because it sounds like the flexis are knackered, and even if they aren't it's the most restrictive part of the stock exhaust after the cats. Personally I'd say avoid Japspeed and go for a decent stainless cat-back system like a Cobra or Scorpion

 

DB

[AngryHippo]

It just doesn't sound like my usual HFCs noise. The raspy noise at 3k revs upon acceleration I got used to and then when I let off the accelerator and the revs drop down to around 3k the cats start their normal hiss/rasp. It's the strange different toned rasp that happens just before it that just doesn't sound right. It's never made that noise before, just seems really strange to start all of a sudden.

 

thanks CS, I will have to have a look at the Cobra y-pipe.

 

Does changing the y-pipe make much difference in terms of exhaust volume and tone or will it stay relatively the same?

 

DannyBoy I have the scorpion cat back system, with the berk HFCs, it's just the y-pipe that's stock. I was looking at the milltek exhaust system, at least with that I would have gotten the complete package including a new y-pipe. Unfortunately I couldnt afford to go with it in the end.

[DannyBoy]

If you still have a stock Y-pipe then you can't have a cat-back. A cat-back will change the whole exhaust behind the cats, so y-pipe, midpipe and back-box. I can vouch for the Milltek as I have it on mine, a very good pairing with the HFCs.

 

DB

[AngryHippo]

Dannyboy I stand corrected, your right, I have the scorpion half system, which is just the rear silencer and link pipe. I have seen quite a few positive comments on hear regarding the berk HFCs and milltek cat back system. Apparently makes a lovely noise when booted.