Okay, I was referred to a local muffler shop by a buddy in my Z club to have test pipes installed on my 08 350z. As i was leaving the shop the car started making a LOUD metal like buzzing sound at about 2000 rpm then fading out at about 3000 rpm. If i take it verry easy on the throttle then i will have no "buzz" at all. before i did this i went on youtube and listened to others who were running test pipes on their oem 350z and they didnt sound like this. Needless to say i am very unhappy with the result and went back to talk to the owner of the muffler shop. he told me that the reason is that after deleting the cats there is too much air flow to the muffler resulting the "buzzing" sound. So gentelmen, my question is what to do to eleminate my problem? do i have them put the cats back on? can i have the oem muffler modified to reduce the buzz? or lastly should i look for a new cat back exhaust system, if that would even help or make the buzzing louder.

Thank you in advance for your help!

-sam

 

you're simply experiencing the natural rasp of test pipes on a 350Z - every single Z with test pipes sounds like this to one degree or another

 

RASP is the word we generally use to describe the buzz

It's blood crawling...I would have them double check the stock metal o-ring wasn't keep when putting in the new test pipes. Also the muffler might not be able to baffle the higher exhaust db note. I had my stock muffler checked and at 30k two of the four chambers where "blown" they said. Also some say there is a break in for test pipes...

All in all you might need to start looking into a whole new exhaust...

MOTORDYNE!

google it!

 

I just went through this but backwards. I had an hks exhaust w/ stock cats for a while. I switched the cats to test pipes and it sounded awesome IMO. Rode that way for 20k miles. I just recently decided to part the z out and put it back to near stock. I put the stock exhaust back on, but left the test pipes because they're a ***** to get in and out (plus I scrapped the old oem cats).

My exhaust now sounds like complete ****. The test pipes and stock exhaust DO NOT mate well at all. I have the same buzzing sound you do, and the nice vq exhaust note is gone. It sounds like a muffled lawn mower between 1k-5k rpms. It doesn't help that I have a couple exhaust leaks, but I have the noise you're complaining about and I hate it as well. Throw a cat back on and you'll be extremely happy.

 

There are so many exhaust combos for the 350Z....you happened to put one together that is not satisfying to you......

A friend of mine has a G37s coupe. First exhaust mod was Berk HFC's. I called his car the rasp monster. When he scored a used Fujitsubo Leagalis R catback it totally cleaned up all the rasp.

There is some Fujitsubo exhausts available in the marketplace. Get paypal ready bro. Or like someone else mentioned, the Motordyne ART pipes do a pretty good job of cleaning up the rasp.

I see 3 scenarios for you

1. Put stock cats back on
2. New exhaust
3. MD ART pipes

Edit: what is your exact set up?

 

What kind(brand) of test pipes?
Sounds like its just a "rasp".I had the same deal in another car I had.
Next time I went to resonated test pipes.
Solved the problem.
Sometimes when you mix components you end up with something you don't like.

 

https://my350z.com/forum/engine/5327...em-50-off.html

Here's a link to the Fujitsubo if you're interested.

 

thanks for the input guys. my problem is that i have set myself a budget for the mods i want to do on my car and if i have to to shell out 500-800 bucks for something i wasnt planning on buying then thats not good. one member mentioned that test pipes had a break in period. anyone care to elaborate?

 

There's no break in period. That makes no sense.

 

Cars are expensive money pits if you decide to re engineer what the kind folks at Nissan did. You could try inserting a cheap thrush muffler somewhere before te catback but do you really want to cut your pretty catback

 

i have the same problem. After my test pipe install, i noticed that the y pipe, right before the test pipe, is rattling against the floor pan. I tried cushioning the pipe with heat wrap but it fell out. It seemed to work if i could just get it to hold better.

 

have your muffler guy make you a oem style j-hook and buy a oem nissan exhaust bushing. They're of the heavy duty rubble style. Have him place it such that it braces the offending pipe away from any direct cross-brace or other metals.

 

I agree, just what other sites say on the topic!

 

Put the catalytic converters back on the car. Problem solved.

 

Put cats back on car or look into new exhaust. But either way the test pipes are going to be loud and raspy and you may even find that pairing them up with a new exhaust is even more loud and obnoxious. I would watch videos on youtube to get an idea of what you would like but even that wont be exactly how it sounds. Every car sounds different....

 

Here's how you fix this problem: unbolt your entire exhaust system from Y pipe to muffler. Then re-install Y pipe and use a jack stand to hold it in place, making sure it's not touching the X brace. Then tighten the bolts from cats to Y pipe evenly. Keep the jack stand on and put on rest of the exhaust system. After they're all on, then tighten the y pipe to mid pipe bolts but remove jack stands first.

Need clarification, PM me.

 

Well, I have had my APS test pipes on for ~ 3 years and yep, it rattles..sometimes worse than others. OP this should have been noted by the 1,000's of posts OL about this. Nonetheless, a great and cheaper way than others to open up the channels.
I stand by my decision, and its loud as phugg....sounds great, and rattles like ish at other times...you learn to love the rattle, or you will swap instantly!

On the track, as w most race cars, it sounds great...street,may take some getting used to.

 

heres my two cents, i have replica nismo headers, replica hks exhaust, regular ol stainless steel test pipes custom, with full air mods i thought thought that rasp was getting milder, i ported n polished my intake mani's, spaced 5/16 lower spacer on collector /thermal gasket/short ram K&n filter,jwt headshielded with the factory fog light plate cut out so a snake pipe connects to it and up to the stock hole for the instake inlet. just something to bring more air to the filter. all said with all this the exhaust was really loud but awesome in its own right, people refer to it as f1 sorta sound. i installed turbo xs utec and got a tune eventually and this believe it or not made the car sound totally different. its a tad quieter no rasp at all! wipe open its still loud as hell. but because race car. now ive always heard if you want to rid this rasp you could also run a X pipe instead of the Y.