Just got my Helix TP installed, non-resonated BTW. Loving it except the hissing sounds (I got no turbo) that always there when it hit 2.5 to 2k rpm. Check out this video I took (you got to turn it loud, pay attention when I release the gas and hit around 2.5k rpm):
<embed width="448" height="361" type="application/x-shockwave-flash" wmode="transparent" src="http://i155.photobucket.com/player.swf?file=http://vid155.photobucket.com/albums/s294/christiannathaniel/VID00001-20090617-1950.flv">

My question is, eventhough I already checked all over the forum, is this normal? I noticed my Intense Y-pipe pretty scraped around the flex area for being too low, is it because of it? Anyway to get rid of it?

Comments or opinions anyone?

 

Do you have a stock exhaust?If so thats your answer ...test pipes+ stock exhaust=terrible sound/hissing/rasp

 

Just listened to your vid, when i had helix TP with stock exhaust...it sounded horribleeee...i took it off ina matter of days, once you get an aftermarket exhaust it will sound amazing......here a vid of my Z with...(helix TP with injen ses Ti exhaust)

http://www.youtube.com/watch?v=jBc24zH49GU

 

Nope, Tanabe Hyper Medallion exhaust, forget to add that.

 

NVM than, just check your bolts up by your headers make sure there is no leaks, other than that i have no idea

 

^^
No he does not have a leak.

That hissing sound is absolutely normal. I have it with my Berk HFCs, my cousin's '04 G coupe has it with Megan V2 test pipes, many clips on youtube have it, it's everywhere.

People have agreed to blame it on the flex sections on the y-pipes.

 

^+1.... i figured it was a leak but...when i had helix testpipes and stock exhaust, it had NO leaks and kinda sounded just like that....but with aftermarket exhaust must be a leak...i agree

 

I have test pipes + Injen TD Ti and I still have hissing. I blame the flex sections.

I just wrapped it in aluminum foil and made the noise go away.

 

Aluminum foil? Never heard about that, interesting. I'm not sure if aftermarket or stock would make any hissing difference. Anyone else would chime in?

 

Its normal my cousin has helix tp too and they make the hissing!!!

 

Aluminum foil is a joke please dont do that. There was another guy in a thread talking about sealing up a busted up y pipe with aluminum foil and some other crap.

 

Maybe the anti-hissing valve is jammed up with back pressure.

 

my borla with top speed res tp hisses too

 

i had that hissing sound until installed my y pipe

 

My turbo XS test pipes make the hissing sound too. Does anyone know if using the mounting brackets helps with the sound? I heard that using the mounting brackets causes cracking.

 

Update: brought the car back to the shop where the TP installed, they put the car on the lift and have one of their crew stepping on the gas. Hissing comes from the mid part of the Y-Pipe!! Dang!! WTF?? I guess I just have to live with it, planning to go to muffler shop and have them to mod the Y-Pipe.

 

Its the flex sections in your y pipe thats hissing. Instead of modding the y pipe just buy an aftermarket one that doesnt hiss. *cough* motordyne XYZ pipe

 

i got the same problem - it only happens when decelerating. if i cruise down hill with engine brake around 2000rpm, the noise continues until either i get out of the noisy area (1800~2200rpm for my car) or touch the accelerator.

My Y pipe is some ebay cheapo, and one of the flex joint is scraped and internals exposed (meshes all torn). However, the noise was happening even when the pipe was in better condition and i wonder if replacing the flex joint would fix the problem. I am more suspecting that it may have got something to do with the Y pipe merging the two pipes and some sort of turbulance being created in the mid section of the Y pipe.

XYZ pipe looks very good, but its rather expensive and unsure whether that would fix my problem or not... I quite like the easy to replace cat/reasonator/pipe idea though!

 

Tonys confirmed with me that replacing your current Y pipe with Motordyne XYZ pipe will stop the hissing.

 

who is Tony?