I know it's somewhere on the forum but I can't find it. I am going to go TT soon and I was wondering if I should get high flow cats or test pipes. I was told that test pipes have a hideous rasp but that is mainly for NA people. I have read that SC people experience rasp as well... I have a Fujitsubo Exhaust and Y-pipe. 76mm piping or 2.99 inches. I don't want my car sounding like straight-piped Civic.

So will test pipes rasp at all on a Twin Turbo G35?

Doesn't the TT make the whole exhaust more quiet?

I read that by running test pipes, you can get more power with less boost. Is that correct?

Thanks in advance.

 

wouldnt resonators help with the rasp?

 

Yeah but I think resonated test pipes would have similar flow of high flow cats wouldn't they because of the perforation inside the piping and extra layer?

 

The turbines will dramatically quiet down any exhaust and minimize rasp as well. I would expect that any good resonated TP will be virtually rasp-free in a turbo application. The flow characteristics of a resonated TP vs. non-resonated is almost indetectable. Certainly not enough of a difference to be measured on a dyno. In my experience, there is no advantage to going non-resonated other than whatever cost reduction there may be (usually minimal).

And yes, TP will help power dramatically on a turbo setup. All turbines like to dump to atmosphere or as close as you can get it for max efficiency.

 

I went from cats to test pipes. I didn't notice any rasp, slightly louder but not raspy.

Comparing my TT w/ Stillen exhuast tone to a S/C w/ Stillen exhaust the TT is quieter.

 

I rode in GRD's G35 with the APS TT and APS exhaust, with test pipes. It sounded just about like stock - with zero rasp.

They said a complaint they hear is that the system isn't loud enough and that some guys want people to hear them coming. (Personally, I'd rather have people see me going!)

 

Good to know. I see in your sig that you're the one that owns that sicka55 FX35. Love it!!!

I am going with the JWT TT by VRT as well. Scott had mentioned test pipes so I was just trying to get everything ready for the install. A local forum member was going to give me a great deal on some HF cats but my buddy suggested that I just to straight to test pipes.

 

Ah, that's what people mean by "dump tubes?"

 

I agree, I don't care for too much noise. I want to hear the turbos spooling over the exhaust note.

 

I can't comment on HF cats, but test pipes really do make a difference for me. You can feel the reduced pressure when you go WOT. I don't think the smile can get any bigger.

You'll be very happy with the VRT treatment.

 

Does it have 2.5" or 3" exhaust? Which size test pipes as well?

 

not exactly. "dump tubes" as discussed in the F/I forums usually means having the wastegates vent directly to the atmosphere instead of being plumbed back into the exhaust... they usually vent into a pair of tubes that point straight down to the pavement. in addition to making the car much louder at times when the wastegates are open, it gives a substantial power increase i believe due to the better flow.

this is only possible on turbo kits that use external wastegates (GReddy & Speed Force Racing IIRC). kits like the JWT and APS, use Garrett turbos with internal wastegates (attached to the turbocharger itself).

somebody correct me if i'm wrong

 

Correct. Whether its on the compressor side or the driven side, a reduction in backpressure improves efficiency. Obviously, spool up time is also improved.

 

I see. Thanks.

Will the "check engine" indicator light come if I use test pipes?

 

Yep, you will get s SES light. Dont believe any claim that these test pipes will not throw a light. THEY WILL. You have to do the no-fouler fix. Search and ye shall find.