isnt there a way to reduce rasp without replacing the test pipes? maybe by wrapping them with something?

 

Test pipes most likely did throw a code, and you can heat wrap them to get the rasp down a little. Rasp will still be there though.

 

It is a common mistake. On older cars AKA hotrods it was very popular to put headers right away. Now that was before all the restrictions we have on our exhaust today. Todays stock exhausts has a plethora of chambers and filters. These chambers resonate under higher pressure, hence the raspy sound.

I do agree that your newly purchase items will crack soon. However you can take a preventative measure. The headers are now allowing more hot air to come out of the engine. This of course is good as long as it can continue to flow just as freely the rest of the way. On yours it runs into the stock parts causing too much back pressure. Your new parts are currently handling more heat than they were designed for, failure is imminent. Your new parts will break sooner or later.

I recommend you finish the rest of the exhaust setup. In the long run you will actually save money.

 

The resonators eliminate the rasp and certain soundwaves. But if you change out the cat, the soundwaves change, and hence the rasp. Go with a straightpipe all the way through and your exhaust will still sound raspy. But have enough air going through the piping and the rasp will naturally go away unless there's something else causing some sort of turbulence (like mismatched piping?).

I'd be more worried about the welds cracking.

 

With the addition of the new headers, best bet would do go with a full catback system to ensure proper airflow from engine to exit.

 

Buy the ART pipes from Motordyne

 

get rid of the test pipes

 

I took the testpipes of and installed Berks HFC.....SAME SOUND!! so it's either the headers (which most people thought they wouldn't make any difference in sound) or there is too much air flow for the stock muffler after all its the only stock peice on my exhaust. Any sedan guys running headers??

 

Went to an exhaust shop today and their performance guy told me its likely both causing the sound, if I want it to go away get rid of the HFC and put my stock ones back on and it should get rid of the rasp. Now he's and exhaust specialist but I don't think he's done much G35's he told me these HFC don't make much of an increase in power at all infact if I were to leave the HFC on and he put a big resonator on the midpipe it would be just the same (for power increase) to just take them off and put the stock cats back on merely because resonators restrict flow, he mentioned HFC and performance mufflers are a very small power increase 3- 5 HP unless your engine is heavily modded.
Any input and or thoughts on this is appreciated, now if any of you are going to say "He's full of it they do give a decent power increase" than please back up your statement with proof like a before and after Dyno pull.....NO but dyno's and no "but the berks website said 15HP increase"......pff please.

 

I can tell you now that a mid-pipe sans resonator is not going to make any power like HFCs do, but the mid-pipe and resonator off of the 05/06 is rated for better air flow, and a nicer sound. My headers don't make a rasp sound, so I'd say it's the HFCs. HFCs make good power because your cats are the biggest restriction in your exhaust, but since you want dyno numbers, you're going to have to do a search. All the info is here, look for it.

But I'd say that unless you get your motor built or tuned, a larger exhaust is losing back pressure and really only shifting power from the low end to the top end, making your car a bit more sluggish in everyday driving circumstances.

 

Thanks dofu for the imput, so you have headers on your sedan do you also have HFC or are you using the stock ones still?

 

What a small world. I did the same mistake. I put megan headers on but after leaving the parking lot of my shop. I turned right around and took them off and just sold them. I just roll with Fast Intentions HF resonated test pipes and a HKS hi power exhaust. Sounds orgasmic.

 

I've gone through HFCs and test pipes, resonated and non resonated, and the resonated test pipes had the least amount of rasp. Every single one of them busted open on me, so I'm running stock cats now. But then again, I've gone through a few cat-backs too. Maybe opening up the exhaust helped, it's been so long, I can't be certain anymore...

 

What kind of driving are u doing Dofu? I drag race weekly with stillen test pipes for over two years with no cracks or problems.


As far as the rasp goes, I replaced my cats with stillen test pipes the rest was stock. The raspy sound started from the stock muffler, it wasn't designed to handle the higher flow and temperatures. Within three months the internal baffles blew apart in the stock muffler causing a crazy loud vibration. I cut it out and welded in a flowmaster. With the flowmaster the rasp was reduced considerably. I spoke to an engine builder from P&L tuning, he said the 2003 engine only has variable exhaust valves and the newer motors have variable intake and exhaust. He told me the ecu would make slight adjustment on it's own and that might eliminate some of the rasp, he was right. After a driving it for a couple weeks it toned down alot but was still there around 3500 rpm.
Now last week I installed headers and a stillen dual exhaust. When I fired it up it sounded terrible so I started investigating. What I had found was the stillen exhaust system used the factory gaskets between the test pipes and the cat back system. The factory gasket is a two layer piece of stainless that has the potential to vibrate if it's not perfectly aligned. F that ish, I ordered new solid one piece gaskets and the sound is 100% better.

Sorry for life story, I get carried away sometimes

 

Check it out, the first video is stock system with stillen test pipes and no muffler


And the next is with a flowmaster muffler, huge difference in the rasp


Here's a pic of my race pipes after 10,000 miles, two winters and two summers of drag racing. All in all a little surface rust ain't bad.