So what's the solution then? Get the stock cats replaced with new ones?

 

After reading everyone's input, plus evaluating my own experiences with this. I honestly think it has to do with a combination of things and not just one thing. The reason for this is because at first I was starting to agree with everyone else that it was the test pipes, but then I realized that I was getting the raspiness sound even before I had my test pipes and headers installed. This is why I keep stating that my setup before I put on the headers and test pipes was the following: Y- Pipe, Mid-Pipe, and stock muffler, also just to mention I had the Crawford plenum and pulleys. Now keep in mind that with that setup I was getting the rasp, but not as bad as I am getting it now. So in my opinion by installing the test pipes and headers to my setup, it definitely increased the raspiness, I still can't pinpoint exactly if it is one specific thing. I will try to see if resonators will reduce the rasp and post on it later. In the meantime anyone else's input is greatly appreciated in this matter. I think everyone who has heard this " raspiness '' agrees with me by thinking that it is exteremely annoying and it makes the car sound cheap! Lets all come together and find a solution to this.

 

I havent been commenting on any deffinate solutions sicne i dont have my resonated testpipes yet. but i do know that kinetix researched this very problem & designed thier resonated testpipes to eliminate approx 90% of the rasp. heck if thier res. pipes eliminate 90% of the rasp on a full exhuast setup w/o hurting theh.p. increase as compared to the straight through pipes than why not go with them or capitalize on this already done research. if we know they designed a pipe that helps eliminate 90% of the rasp then we know that all or at least most of the problem lies in the tstpipes right? they could eliminate all of the rasp but then h.p. would suffer..........i truely believe that the sound is from the engine & is just amplified by the freer flowing exhaust sytems, especially in the midpipe area..........i just think that the stock catted pipes just do a great job of muffling the sound. the cats are just so heavily packed with crap that they have the most sound deadning type material of any other exhaust item..........so when i learned that kinetix researched this & designed a pipe that eliminates 90% of the rasp w/o hurting the performance gains i jumped on it. i cant see why others arent opting to add resonators instead of just trying other brand pipes just to find the same sound!
all in all we know the sound is always their but the pulses/waves in the axhuast are amplified as we enlarge the exhaust & free the flow up. then once we eliminate the "sound deadning" cats we open these pulse/waves through the exhaust & hear the annoying rasp. SO, add resonators to the testpipes to help deaden the sound. the ore you want to deaden the sound, the more h.p. loss there will be over the max potential from the straight through designs............i know i repeated alot of stuff that has already been touched on, but it seems so many are still trying to figure out how fix the rasp...........

-justin

 

You're so right! I'm a mechanical idiot, so no help from me.

 

I have:
Borla TD exhaust
JWT Pop-charger
R/t Cats

I sometimes get a VERY slight metallic sound when WOT past 4k. But it is barely noticeable. Once I hit 5.5 I can't hear it. Most of the time, I can't even hear it. What I do get is my exhaust becomes very, very loud between 2.6-3.0k. It makes a very deep drone that is pretty loud. Anywhere else in the rpm band it is normal.

Also, when i'm off the throttle slowing down, i'll get a hisss sound from about 2.5k to 1.5k. It is louder than the rasp that I hear.

 

How many people have intakes or plenums added? I only ask because I wonder if there is any corelation to the air volume and the raspiness. Just a thought.

I still think it has to do with the VQ head/block design. Has anyone ported and/or polished their heads?

Resonators, etc. are only a Band-Aid to the raspiness problem. The noice is emanating from somewhere. It is only a matter of locating the origin. Aren't there any stereo aficianados who can install microphones under their cars and inside the engine bay to monitor this noise? Just another thought.

 

I also found that the car has quite a drone at those RPM's. I installed the Borla with Kinetix cats and had a horrible drone. My wife and I both could not handle it during trips, so I took off the Borla and kept the cats. It now has a very, very slight drone at those RPM's, but nothing to notice unless someone already told you to listen.

 

Ok, so it's not only me. When I had my stock cats and borla exhaust, it didn't make this sound. At least it wasn't perceptible.

I love the borla exhaust, and like the gains from the HF cats. So what I did was I recently dynamatted my car. I am also going to put a layer or 2 of Dynaliner, which should help alot in taking out some of the sound.

I posted my dynamat experience/install here:
http://forums.freshalloy.com/ubbthre...1#Post67759928

 

The statement of the resonators only being a bandaid for the rasp sound isn't totally correct, it(highflow resonated testpipes) are a power adder that aids in the rasp sound. Its not like sticking somthing on that looks awful or effects performance to eliminate somthing. I don't think the rasp is a sound caused by a problem with the z, its obviously somthing to do with the engine/head setup on the VQ design. I agree highly to keep researching to see if we can find the exact origin if the rasp, but I don't think adding a resonated cat is somthing bad if it eliminatres the rasp, especially if it can be done w/o comprimising the h.p. Gains of the testpipes! Untill somones finds out exactly what the deal is the resonated test pipes are great if anyone is deciding on going the testpipe route or wanting to help eliminate the rasp in the meantime. I can't say for sure but I believe some possible headwork or possible internal fabrication will need done to totally eliminate the rasp. So if the resonators help fix it now or stay used as a permanent rasp elimination scource while adding h.p. Then go with it! Its not hurting anyhting. Also if it does turn out to be an internal problem some of us won't have the time or funds to dig inside to get ti eliminated...........point being, the resonated testpipes are all we have right now for the solution, so we can start here in the meantime........just my .02c

-justin

 

Justin,

I am looking to get the Kinetix w/ resonators. Do you know where I can get the best price on these??

 

f2dmfine, im not sure of anyone else that sells kinetix parts other than kinetix. i ordered them directly from kinetix. i ordered several kinetix products at one time & got a great package deal so i felt real comfortable with the purchasing price.

who knows, mabey a possible group buy purchase if enough here are tired of the rasp! could potentially get a great deal...........just a thought.

-justin

 

I am going to have to disagree with you. Everyone here is looking for a Band-aid fix. Meanwhile I never disputed the fact that the testpipes were are a power adder. Imagine you had a leak in your roof that drips through the ceiling. You patch the ceiling so you can't see where is leaked, but without finding the source of the leak, you haven't cured the problem.

THAT sounds like a problem to me.

Still sounds like a problem.

And, this is called...


a Band-aid.

 

ok, ok...im not looking to start an argument over a "band-aid" issue. we see this as a problem because of the sound we hear, not how the car performs, so is it really a problem with the cars design? well, it seems to be opinionated. to those who like the sound, odd i know, its not a problem. but to us who dislike the raspy sound it is a problem. so with that being said, ill stay with the kinetix resonated pipes that adds the h.p. but doesnt allow the rasp to come through since i believe there isnt a performance problem that needs touched on & in my case, no sound problem either! i know the "problem" is pretty general, so well just have to let our feelings of opinions aside, though deffinately stated. i truely hope that somthing can be tracked down for those who think there is an internal design flaw...........

-justin

 

I just hate the fact that my car sounds like it has a honda fart cannon installed when i gun it. I love the power but it sounds like a motorcycle or a 4cylinder engine when ever i am at WOT or close to it. I am going to have to order those kinetix test pipes with resonators. I will probably seel my B@B race pipes.

 

I just installed the Helix test pipes and I haven't heard any "raspyness" yet??? Even @ 3500-4500 RPM's (where most people say it is heard) I have the Borla TD...the car now sounds more like v8 rather than a v6. I'm happy.

 

I'll politely agree to disagree regarding the raspiness/potential design flaw discussion.

Meanwhile, are you referring to the Kinetix High Flow Cats, or does Kinetix have a separate resonated test pipe which I haven't seen?

 

It's pretty obvious people are not reading the entire thread when replying. We are starting to go around in circles again about whether it is test pipes or mufflers or cats or which brand of X.

Between all of the different exhaust systems, every single component of the exhaust has been replaced and the buzz is still there. People on the board have replaced every component in the exhaust system from the Headers to the Mufflers.

The only thing no one has tried yet, is removing the O2 sensors. They have a thin metal cage around them that could be vibrating.

The part that is always put back in is the sensors. Maybe it's not the O2's, but until someone pulls them out, we won't know. If it turns out to be the sensors, than we can look at aftermarket for some that won't buzz. Another possibility may be to place a couple of washers around the threads so the they won't sit so far into the pipe.

The stock cats have a metal screen in the path of the exhaust to make sure the gases flow into the catalyst section. I think when you put high flow cats or test pipes in, the exhaust gas velocity increases enough to cause the metal around the sensors to buzz. This is why test pipes and high flow cats are making decent power. If you get under the car you can hear it buzzing right around the area the sensors are mounted.

You will get a CEL if you remove them, but it will go away once you put them back.

I would try it, but I sold my test pipes because I couldn't stand the raspiness. Would sure love to get the power back!

 

Gamblerz, yes kinetix designed some resonated testpipes separate from the straight through & the high flow cat design. They were made specifically to eliminate this rasp sound. I posted the description directly from their website about these pipes back a few posts here.

Zship, I would like to see how the 02 sensor removal pans out as well.

-justin

 

In the performance diesel camp we often battle drone/raspy exhaust tone and one of the prime tools is to weld pieces of metal, such as round stock, to the tubing. This changes the harmonics and can often eliminate drone. The normal procedure is to pick the longest straight piece and add a piece or two there and run it and see what you get. Move on to the next longest run, etc. The places to look are the straighter chunks and the longest pieces that do not have a dampener such as a cat or muffler. A little creativity in placement can keep these out of sight for the most part if that is a concern. Normally with a little screwing around a marked improvement can be achieved. I don't know if this translates over to the gas world or not but it seems like it might be applicable. Anyhow first post here, Hello.

 

welcome to the board crabman, very interesting piece of information you left us, thanx...........

-justin