Ok... here's the Cliff's Notes:

Installed test pipes some time ago (Strup), things went well for thousands of miles... then developed a rattle/leak. It was the expansion joint on the factory y-pipe.

I purchased a Nismo S-Tune exhaust... fixed the problem for about a day. A few good pulls later, the problem returned with authority (rattle/leak). One rattle at 1800, another bad one around 2400-2500.

The test pipes are unsupported (no bracket), which is what I suspect a part of the problem. The y-pipe rattles a lot just beyond the expansion joint.

I need to fix this problem ASAP as my Z is currently my daily driver. Any suggestions or ideas? Maybe some decent high flow cats or test pipes with a good bracket (or use the stock one)? Ideas for a replacement mid-pipe that will fit my less than a week old Nismo? I tried using a metal bracket around the y-pipe in an attempt to limit or fix the problem but no luck.

As the saying goes... gotta pay to play. I'm a student of the school of hard knocks. Any help is appreciated.

 

Is it a rattle or leak , a rattle is perfectly drivable.

 

i developed the same issue. I have TurboXS test pipes and Greddy Ti-C exhaust. my test pipes are unsupported due to the fact when they were supported they cracked. I had to just replace my stock Y pipe because one of the flex pieces had a crack that rattled ery bad. Sounded like a monkey trying to beat my floor board in. I just replaced it today and it seemed to help the noise.

 

Both... the rattle is a lot worse than you might think. The rattle is (mostly) from the movement of the y-pipe. The leak is coming from the expansion joint as a result of the extreme vibration.

 

Test pipes with the NISMO exhaust have caused members lots of headaches. Not sure why or the fix. Helix SS Test Pipes have a mounting bracket. 6,280 miles and no problems. Knock on wood.

 

TP's with Nismo sure is a headache. Trust me I know. The my Y pipe has a rattle that sounds like a hiss when the engine is slowing. Its common on the Nismo. There really isnt a fix as far as I know. Ive gone thru 4 different sets of TP's because they've all cracked. Try some HFC's and see if you have better luck with that. Good luck man.

 

Thanks for the responses.

Anyone else have long term good luck with Nismo and the Helix SS TP's?

Any high flow cat's out there that use the stock support bracket?

I'm toying with the idea of gutting my stock cats, but I'm guessing that could turn into a headache.

 

the problem is not necessarily having or not having a support bracket - I've done in both ways with a wide variety of exhausts and never had a problem

the trick is in the install and the order your tighten the bolts - start loose, going in to opposite corners when tightening, and I'd bet you will not have a problem. Doing it the way I see most do it (fully torque one flange then the other), tends to put alot of strain on things.

 

Hmm... I'll need to order a good midpipe, and figure out a replacement for the current TP's. Anyone with Nismo that can make a solid suggestion? I have my credit card in hand. Haha. I just don't want to mess with my exhaust ever again! At least not on this Z.

 

Anyone know a good replacement midpipe that will work with Nismo???

 

I've yet to see anyone offer a midpipe alone...best bet is to go have one made at a local exhaust shop I'd think

 

My Nismo exhaust broke the support brackets off of the Helix test pipes

 

 

What would you guys suggest to permanently solve the problem?

Right now I'm thinking throw the stock cats on... see how much that helps, but I'll still have a leak and I'll lose the gains. Sucks.

 

So wait, what happened to the midpipe exactly?? My midpipe rattled a little with test pipes. Never was sure what caused it.

 

Easy fix for all of you.

You'll see a chassis bracket right above the y-pipe. Go buy the exhaust strip and strip tight the y-pipe with this bracket.

Reason you hear rattle is because after you install aftermarket exhaust. The exhaust pipe sit too low and the mid-pipe is hitting another chassis bracket. I had very bad rattle but after I strip the y-pipe. All rattle are disappear.

 

It's hard to describe, but he we go:

If you look under my car, from around 2100-2500 rpms my exhaust vibrates violently (moving around a half inch or so) after the expansion bulge on the y-pipe. This happens mostly on the drivers side and occurs AFTER the braided expansion joint (not the side that connects to the TP/cats). This extreme vibration is causing the expansion joint to leak.

The stock exhaust experienced this as well, but took some time to develop (thousands of miles) after the test pipes were installed. The only thing I can figure is that the strup test pipe flange is set at the wrong angle causing excess stress on the y-pipe (ie. bad fit). Because that the expansion joint is leaking.

It's a bummer... the Nismo sounds jacked. I don't mind spending some money, but I want to get this thing fixed.

 

I'm sorry but you should not have to remove any part of the car to fit an aftermarket exhaust - if you do, you either bought garbage parts (garbage in, garbage out), or the install was done carelessly and caused an issue

By your own post, your test pipes are causing your problem. Why? I have no idea. It's not a brand we sell nor do I have any experience with. But I do know that there are enough test pipes on the market that are issue free that you should not have to deal with such poor results, in the short or long term

The unsupported nature of your test pipes is not the problem. What could the problem be? The order you tightened the bolts as I mentioned above, or the flanges not being 100% square, thuse causing strain on the rest of your setup. If you fit a bracket to this existing setup, my guess is that it now will break at the bracket. That certainly is not the answer you are looking for.

I will say this.....most times on these things, it's the install (ie the order in which its all tightened down) and not the component itself. You wouldn't think its hard to install test pipes, and truth is, they aren't. But there is a right and wrong way to the order of the bolts, and most times I've watched people install their own, it's done wrong (ie they tighten one flange fully, then the other)

 

The problem is the nismo exhaust BLOWS.

 

??? The only thing that was ever removed was the cats to install the test pipes... so I'm confused by that portion of your response because nothing was removed. The stock exhaust was removed by a well know performance shop in my area... they do quality work, and have experience with Z (tt kits, etc.) but I didn't watch my install, so I don't know.

As for the install on the test pipes I did it myself alternating tightening bolts on opposite sides... all torqued to the same spec with my torque wrench. I did the same for a buddies Z around two years ago without any issues at all. The fit wasn't horrible, but it wasn't perfect either and I suspect that was the problem... thus the angle of the flanges. My guess then would be garbage part.