I was trying to find a clip of rasp because the noise you're about to hear is what my exhaust sounds like. I've got the Berk HFC's + Borla and it looks like this noise problem is common with most TP's and HFC's. (I haven't heard "rasp" yet, so I'm not sure if that is what my problem actually is. That's why I need your help!)

Anyways, here are the clips (Not my car, but similar noises w/ different exhausts):
http://www.youtube.com/watch?v=6Fyc8oEUz7I
http://www.youtube.com/watch?v=Y_FMsIDBusQ&NR=1

 

I have the same problem when I installed my hfc. I dont think it is rasp.

 

Thanks. I'm just trying to determine what "rasp" sounds like so I know it when I hear it.

I'm already scheduled to get my Magnaflow X-pipe swapped for my Borla H this weekend, and I'm hoping this will help reduce that noise.

 

Rasp sounds like a rattling tin can.

 

Maybe it's the crappy quality of the video / sound, but that's what it kinda sounds like to me. I'll post up a good video of the sound when I get home today. Mine really does sound like a "rattling tin can" on the downrev.

 

Adding test pipes will make strange noises. My exhaust sounds like chirping birds. Call it rasp or whatever you want.

 

^^^ Lol~ Mine sound like two rabid squirrels doing teh wild seks~ JK :-)

OP, if you have a TD exhaust, an x-pipe has helped others in alieviating rasp.

 

non-resonated test pipes on the 350Z=RASP! some people like rasp, i dont personally.

 

Yeah, I was looking at some of the comments like "OMG, whats that sound after you rev? I love it!". I don't like it because it feels out of place... I'm used to rev and clean sound, not rev then *BLURFJSDVVVVVVLJVLV* sound.

I don't have TP though. I have Berk HFC's and the reason I am doing the X pipe is because of the comments on this site about alleviating rasp. I'll be sure to post a distinct before and after vid to show the difference.

 

rasp?

...

THIS IS SPARTAAAA

 

Is it the type of muffler, test pipes, piping, or what that causes rasp. That is probably a dangerous question. I just want to know if there is some similiar reasoning behing what causes rasp?

 

Test pipes or aftermarket cats is pretty much the number one thing in common. Mainly because there is so much more flowing through the exhaust. Piping is also a factor, but I don't think it's as big of a deal.

Why I think so:

I can put my stock cats on my Borla and eliminate the "rasp" or whatever.

or

I can leave my HFC's on and put my stock exhaust back on and get no rasp at all.

The "rasp" noise doesn't come from the cats / HFC's though. On the Borla you can take a board (or something to block sound) and go under the car while someone revs. As you use the board to put between you and the front of the car (while slowly moving forward) you can hear the sound coming right from the H-piping on the Borla.

 

The weird thing is that I have that same sound coming from my Berk Test Pipes. It sounds like metal vibrating on metal. I have no idea what it is but my car just started making that noise not that long ago. It wont do it just parked it's under load at around 3K. I know what rasp sounds like but this is totally different than what I'm getting. Can't figure out what it is.

 

Yes, that is rasp, in both of those videos. You want a loud, free flowing exhaust? Expect that noise then. Why do stock cats and/or a stock muffler eliminate it? Because they do a better job of muffling the exhaust noise. I have had resonated test pipes, and Crawford cats with my EVO2. Both made the car louder, and both made it sound like garbage. I went back to the stock cats and decided to save my money for FI (turbo's do a mighty fine job of eliminating rasp). I'm tired of these NA mods that cost $500 and give you 3hp.

 

Its a combination of components, exhaust velocity and volume. No one component is responsible for the overall “sound.”

 

I don't think that is rasp. Alot of people that swap out there OEM cataliyic converters to either HFC or Testpipes experience this hissing. I've contacted Berk, the maker of my HFC, and they confirmed it's because of the mixing of exhaust gasses. I'm not sure how to explain it in a more scientific way, but I get it too

 

I have borla exhaust the noise is coming from the small H in the pipe after the cats or Tp's . I had my car on a lift and that noise is coming from that H. My guess is it needs to be larger and have a flow pattern like the magnaflow X pipe. So the exhust flows smother. I went through 3 different test pipes to get the best sound and performance and finally got Kinetix Resonated Test Pipes which have hardly no rasp.

 

Just throw the X-pipe muffler on the Borla. You will get no rasp with test pipes, your tq will improve, and it sounds great. Also the H-pipe has a tendency to crack.

 

My install got delayed until Monday Can't wait to see the results.

 

that made absolutely no sense