I just replaced my cracked Megan y-pipe with the Topspeed after i test drove the car it makes this loud hissing noise when you let go off the gas. I thought i had an exhaust leaks but all bolts are tight. I have a Topspeed hfc also but when i had the Megan on before it didnt make that noise only when it cracked. Is this normal or there's something wrong with the y-pipe? Any info would be appreciated. Thanks.

 

What could be wrong with a y-pipe? You used 3 new gaskets. Proper size. They are all tight?

 

My test pipes do the exact same thing and they're properly installed. Anytime you change the diameter and layout of your headers/y-pipe/test pipes/cats/midpipe/muffler, the sound is going to change whether it be so slight you can't tell or enough that its clear as day.

 

Check leak again and gasket as well.

 

I used the gaskets that came with the y-pipe and i hand tightened the bolts really good.

 

I told one of my good friend and he's a fellow forum member on here, he said that the noise is normal because he had change his stock cats with the TP's and it makes that whistling, sharp hissing noise and it's not a leak. Also he has the same Y-pipe as mine so i guess i have to deal with it. Well thanks everyone for your inputs.

 

Its may be because the flex joints don't have the smooth internal liners.
Most aftermarket Y-pipes have unlined corrugated bellows exposed to the flow stream.
It can cause all kinds of turbulence and noises.

 

Now that make sense, thanks alot Tony!

 

damn ur megan y pipe cracked???

not sure if i want one anymore then..hmm

 

Do you have a sudden bottleneck in your exhaust set up? Usually, the sound is more evident when you go from a larger diameter piping to a smaller one (not the other way around, though) due to turbulence.

 

I was doing a search on the same issue (fluttering sound when off load). From what I've been reading, it's the TP or flex joint making that noise. However, I've noticed another sound with my setup which is TP's, y-pipe w/flex joints, single exit exhaust. I can't stand the fluttering sound when letting off the accelerator, but my main concern is the sound coming from the flex joint.

When under load, the driver side flex joint makes a nasty buzzing sound which I have identified as a leak. So instead of buying a brand new y-pipe or flex joint to be welded in, I've thought about getting rid of the flex joints.

I don't think I've ever seen a comparison. I know people post about each preference, but I'm wondering why some have flex joints while others don't. I'm beginning to think that maybe the ones w/o the flex joints might be better since there's less to break. I'm seriously considering having my y-pipe fixed to delete the flex joints, but I wanted to know if anyone has done it and what happened with that.

Thanks in advance.

 

^ If you do that, then there wouldn't be any "play" in your exhaust system. Under hard acceleration, for example, the torque produced moves the engine, which in turn moves the exhaust components. Without flex joints, you're only adding stress onto other weak spots, which usually means broken welds or cracked pipes (I've had both).

It makes sense logically and it's what I've experienced. I've broken my y-pipe several times, welded in new flex joints, been through 5 or 6 different test pipe set ups (broke most of them ), etc.

I guess the flex joints matter more if you like to race (especially drag racing and the launches).

 

Damn you. Why do you always have to make sense?

I guess I should be buying another flex joint then. Either that or a true dual exhaust system.

BTW, your avi is hypnotic. I could barely type this....

 

I went with a true dual exhaust system after trying a couple of different set ups -- APS 2.5" with X-pipe welded in (has flex joints too).

And I hear that a lot about my avatar. It's been up for a while but I still stare at it everyday. Jessica Alba