spf4000

My car rattles during idling when I come to a stop after the engine heats up. The rattles will stop after about a minute of idling. I can make the rattles stop by pressing on the left cat. But I still haven't been able to isolate the cause because I can't get the car up on jacks quickly enough for me to look under the car.

myz8a4re

iTrader: (2)

well, i just finished reading this entire thread & it scares me to purchase a set of test pipes. i have a couple questions that i didnt grasp during reading the thread: (1) is the rasp appearent with all the test pipe versions(catted, noncatted & resonated) or only the noncatted/nonresonated versions?......does anyone have the resonated high flow testpipes from kinetix? i saw they have the regular striaght through design w/o cats/resonators, a resonated style & a catted style. the description for the resonated style describes a cure for exactly what you all have been talking of, heres the description from kinetx website:
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"Stainless Steel Test Pipes with In-Line Resonators for the 350z and G35 (2dr and 4dr)
These pipes replace your factory catalytic converters, letting all the exhaust pass through freely, but not the noise. Plain test pipes offer the highest level of flow, but often result in a "raspy" exhaust note between 3-4k rpm. Test pipes have always been high on the "bang for the buck" list, but the louder exhaust note can be too aggressive for some people. So we now offer a full stainless straight through converter replacement, but with a stainless exhaust resonator welded in-line. This gives an equal amount of flow, but without the raspiness. The exhaust note will only be slightly louder, and have a slightly deeper tone."

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seems like the testpipes to buy! has anyone tried these yet? the hp gains are identical to the nonresonated version! curious to hear about these!

thanx,
-justin

F2dmfine

Sorry about not posting earlier, I was on a cruise with my wife for a week. Just got back yesterday. Well I have only bad news to say about the whole " raspiness" I took my car to a shop in Miami, called Dynamic Turbo. They have been around for quite a while and have worked on my previous car ( RX-7 ) Anyway back to the story. I would first like for everyone to know exactly what modifications I had on the Z before I installed my headers: in order of install

1. Crawford Plenum
2. K&N drop-in
3. Japtrix Y-Pipe & Mid-Pipe combo ( please keep in mind that I still kept my stock muffler with this setup.)
NOTE: Right after this is when I started hearing a small " rasp" between 3K-4K RPM
4. UR Crank Pulley

I had the DC Sports headers installed along with cat-delete stainless steel pipes. All I can say is that the raspiness went from small to HUGE!!! It got much louder and more noticeable on all RPM's. Well obvious to say it sounded like total Sh*t! The owner of the shop told me that he thought the noise was from my stock muffler not being able to handle all of the freed up pressure and velocity. I knew that this wasn't it but we went ahead and tried it anyway, so he took out my mid-pipe and stock muffler and installed a Borla. This made the exhaust tone a little bit deeper but the Raspiness is still there. Right now I am in a bad situation because while I love the performance that I am getting ( the car feels much more powerful ) I can't stand the sound. I have been reading about the Resonators helping, but right now I don't want to put anymore money into it unless I can be sure of getting rid of this horrible sound once and for all. If I can't get rid of the rasp then as much as I would hate to do it, I might just go back to the stock setup. If anyone has any solution to this please, please help because i know that I am not the only one with this problem. I mean we all want to make our cars faster, but at the same time we don't want them to sound like sh*t!

myz8a4re

iTrader: (2)

wow, these stories are scaring the crap out-a-me! can anyone vouge for the sound from the midpipes from kinetix with the resonators?

-justin

BrianLG35C

iTrader: (2)

Man that sucks! Back to the drawing board.

GamblerZ

iTrader: (2)

I am inclined to agree with you here. The *only* common denominator on *all* these exhaust setups is the aluminum block and heads. Has anyone ported and polished their heads yet? Could it be the open deck creating some harmonics that were muted with a quieter, more restrictive exhaust?

Just food for thought.

F2dmfine

Bump

myz8a4re

iTrader: (2)

well, since you guys scared me away from the straight through testpipes i ordered the resonated style from kinetix lastnight. i also ordered the intake & front/rear camber arms so im pretty stoked......i hope i never hear the "rasp" you all are talking of!

-justin

BrianLG35C

iTrader: (2)

Anyone have any luck solving this??

chaparro78

iTrader: (2)

Stillen headers
Stillen dual exhaust
B&B test pipes

Last week when i had this installed, another guy had the same setup but with no test pipes. He was using the stock cats. As they were installing my set-up he took me for a spin and his stillen setup sounded great, a real deep tone. When they were done with mine I had a raspy noise from 3k to 4k in the RPM range when i was accelerating. It won't produce it when reving though. I am 99.9% sure it is the test pipes. I am going back to either put the stock cats back on or have some resonators installed. I would rather have the car sound good and lose 5hp than have it sound like a civic farting.

GamblerZ

iTrader: (2)

From this, you almost have to consider that the stock cats were "tuned" to eliminate the buzzing. Therefore, I would like to know what the results are of those who have hollowed out their OEM cats?

myz8a4re

iTrader: (2)

ok, we know kinetix does thier research. they made these resonated testpipes exactly for this reason as you can see the statement from thier website that i attached above. so by this we know that the resonators eliminate the buzz/rasp. i would guess that the stock pipes would eliminate the rasp if the cats were gutted since the sock pipes are resonated as well. i think the style/size of the resonator(s) effects this noise more/less. for example, i beleive kinetix eliminated 90% of the rasp while not hurting h.p., i believe that if they eliminated it 100% than h.p. would be hurt & the testpipe gains would no longer be a good "bang for the buck" mod as you may then only see a couple h.p. improvement tops............

-justin

jjellyneck

Not sure if I mentioned this earlier, but I have the stock exhaust with Kinetix cats (my only mod). I have no raspiness at all.

RCKTDAWG

"Not sure if I mentioned this earlier, but I have the stock exhaust with Kinetix cats (my only mod). I have no raspiness at all.

Put a new Y-Pipe on and you might. The stock Y-Pipe is very restrictive. After I installed my JIC Y-Pipe (RT Cats earlier) it ran a lot better but I noticed the buzz.

jjellyneck

Put a new Y-Pipe on and you might. The stock Y-Pipe is very restrictive. After I installed my JIC Y-Pipe (RT Cats earlier) it ran a lot better but I noticed the buzz. [/B][/QUOTE]

You're probably right. That is a goofy looking Y -pipe with a restrictive flow. But I just wanted to mention it as reference---that high flow cats with the stock exhaust have no rasp.

sschmuve

iTrader: (1)

I'm starting to think the stock cats are the problem. It seems like they will normally develope a buzz with age, and high flow aftermarket exhausts don't have enough backpressure to suppress the vibrations as the stock does.

spf4000

You might be right about that. I'm thinking about removing my Nismo exhaust this weekend and switching back to my stock set up to see what will happen.

bwzabodyn

iTrader: (2)

This is the exact reason that I am not going to buy any complete aftermarket cat-back exhaust... I am going to go the custom route and try to use everything that I've learned to counteract the raspiness from my test pipes while developing the sound that I want... and the good part about is that if I'm not satified w/ anything, I'll just cut it out and try something different!

Here's the setup I'm going to try 1st:

Helix Test Pipes (already installed)
to
A custom X-pipe made from 2 Magnaflow Y-pipes
to
Two 4"x18" round Magnaflow mufflers to use as resonators
(which I think will be the key to solving the raspiness)
to
Two Pro-1 Universal GT-1 Style Canister Mufflers w/ Angled Tips

I know of a g35 sedan that has a similar setup (but uses high-flow cats and different mufflers) that sounds great and doesn't have the raspiness (to the best of my knowledge)... I should be undertaking this project beginning next week so I will make sure and keep everyone informed...

BrianLG35C

iTrader: (2)

I'm very close to dumping my RT Cats and going with Ultimate Cats! How's the sound with these?

rodH

iTrader: (2)

don't waste your time, it is still there