Hello, all. I recently had a new Magnaflow catback and Invidia test pipes installed on my 04 350Z. I have no other performance mods yet. The exhaust sounded good, despite the expected rasp and hiss.

Yesterday I accelerated pretty hard and when I returned home and was backing into the driveway I heard a horrible sound coming from the exhaust area. This morning I heard it as well.

I did a quick glance under the car without a lift and didn't notice anything obviously wrong. Any opinions on what could have happened, why, and what would be done to fix the problem?

I had planned on getting everything welded eventually. Maybe it's time for that. I just hope i didn't ruin my exhaust because I no longer have the stock. Thanks for the help.

 

Maybe something came loose? Did you run over something?

Did you install it or have someone else install it? If somebody else did are they a reputable shop? Test pipes are a PITA to install on the Z so maybe they half-assed the install.

You don't need to get everything welded. What is the point of getting a bolt-on part if you want it welded?

 

Im betting its an exhaust leak. Its possible that a bolt is loose or fell out and a gasket blew. Im not sure why you would want to weld it together but its your stuff.

 

I didn't run over anything. I had a reputable shop install the exhaust and three weeks later I had a less than reputable shop install the test pipes. He was the only guy who would do it because it's illegal to remove cats.

I was going to get everything welded so that things don't come loose as easily.

 

I just peaked under the car again and the rattling sound is definitely coming from the test pipe area. I called the guy who installed the test pipes. He told me to come in Saturday at 0900. Strangely, I saw a plug hanging. It looked like something was supposed to be plugged into the other end. Just doesn't look right.

 

IIRC the only connectors up in that area are the O2 sensors.

 

If it is rattling you're hearing, I believe it is a quite common issue with test pipes.

https://my350z.com/forum/intake-exha...le-thread.html

https://my350z.com/forum/intake-exha...ent-issue.html

https://my350z.com/forum/intake-exha...e-install.html

It seems that some people write it off as 'rasp' and others have turned to more proactive measures to *attempt* to get rid of the sound (wrapping the exhaust, among other things).. but i'll leave these here so you can read about it.

 

I just returned from the mechanic that installed my test pipes. The good news is the test pipes and catback are fine. The bad news is the flex pipes need to be replaced. He says it will be $350 total. I scheduled an appointment for next Saturday. He also said I could put a Y pipe on and that would replace the flex pipes.

Thoughts and suggestions? Is $350 for parts and labor too much for flex pipes? Should I just spend double on a Y pipe?

 

What are the flex pipes? Are you referring to the flex portion of the Y pipe? If thats the case it is a brand new exhaust and should not happen at all.

 

Yes, that's what I was referring to. If that shouldn't happen, then what could be the problem? The mechanic stated that was the problem. I understand that he could be wrong, but the test pipes and exhaust checked out fine. The sound is coming from that general area. Everything sounded fine until a few days ago. I need to figure out what the problem is because the sound is absolutely horrible. It sounds like a Geo Metro with a leaky exhaust sputtering down the road.

 

You said you didn't hit anything, so the y pipe wouldn't just randomly break or have damage. I am thinking an exhaust leak at a flange and the mechanic is trying to charge you that price for tightening one bolt.

Can you get under the car and take a picture to post? Be safe but if you can it can help us help you.

 

I'm going to try to get under there this evening after work and snap a picture. I should've when the mechanic had the Z lifted in the air. He pointed to the two flex portions of the Y pipe and claimed they "go bad." I couldn't tell whether or not they were damaged or not. The flex portion looks like a weaved fist-sized bulge in between the test pipes and mid pipe. I actually have never seen them before.

On Saturday I'll be taking my car to the same shop that installed the Magnaflow, but wouldn't install the test pipes. I'll see what they say. If they say I need new "flex pipes" or a new Y pipe then I'll believe it. If they say it was just a bolt I'm going to be pretty upset.

Thank you, and everyone else, for the help. I'll keep you posted and get a picture of the underbody as soon as I can.

 

They are not supposed to "go bad."

They only get ruined if something is ruining it. Either it gets hit, after time with scraping on lowered cars, or too much movement that wears it out, but that would take a while.

Exhausts are not wear-and-tear items. Yes over time you can get rust or damage and may need replacing, but typically they are supposed to be good for the life of the vehicle. Considering where you live I doubt you have to deal with what we have to deal with in NY in terms of external factors such as salt, snow, crappy roads, etc, so your exhaust should last.

Of course if it was installing incorrectly the components could have a shorter life, but lets face it, if you had no issues then IMMEDIATLY had this issue, I have a feeling something fell off or broke. Maybe the part was defective? I am not sure.

But yes definitely post pics and good luck.

 

I took the Z to a very reputable shop. It's the shop that installed my exhaust. I do in fact have an exhaust leak at the flex portion of the Y pipe. I was quoted $172 total to replace and install the part. I think that's very good. I decided to hold off on ordering the part through the shop because I'm going to research aftermarket Y pipes. I'd like to switch to a true dual.