I plan on using Fast Intentions test pipes with the HKS knockoff on my VQHR. People have told me that removing the cat can cause "back pressure" issues. However I never see anyone complain about this problem on the forums and tons of people run test pipes. Can someone educate me on how this works?

 

you'll lose low end power and gain some high end power

backpressure is what keeps the exhaust velocity moving fast which gives you more tq at lower revs and better gas mileage

 

Do you run TPs or HFCs Sentry?

 

large 2.5 inch HFC

 

I have the HKS true dual and with test pipes it is very loud. I would recommend HFC. What test pipes or HFC do you all run with your HKS true dual system? With little rasp...

 

 

I have the amuse titanium test pipes. They aren't resonated. It sounds nasty as hell but it just LOUD! I will make a video clip.

 

The need for backpressure is a myth, properly sized pipe to keep velocity high is what you are aiming for. Anyone who tells you "you need backpressure" does not know what they are talking about.

That said, I don't believe in running cat-less because the difference in gains is small compared to the environmental advantages.

Chris

 

Go hug a tree. You probably believe in global warming and voted for Gore. Seriously though, the backpressure issue has been discussed to death and there is no clear agreement. I would have to yield that a large diameter, low backpressure exhaust WILL kill your low end performance, but improve it at high RPMs. Whether bacpressure is good or bad is moot. The results are what counts. I think the HFCs are a great compromise for drivability, performance, noise, and the environment . I have done test pipes, and the performance difference from a good set of HFCs is insignificant - the price isn't.

 

I installed resonated test pipes a few years back and I can vouch that test pipes do indeed make a difference in horsepower, even running NA. I could tell a bigger difference in top end than low end. Plus with the test pipes, the exhaust note sounds like how it should have come from the factory. All my buddies rag on me about killing the earth, but hey, so do antique cars and you don't see the government making the classic car owners add catalytic converters (at least not in GA).

BTW: I had straight test pipes before my resonated pipes, and I HATED the rasp. It was unbearable in the winter, sounded rice x 100.

 

You don't know me or my politics and bringing it up is just topic misdirection, I'll stick with the topic at hand.

Consensus has nothing to do with facts.

I would have to yield that a large diameter, low velocity exhaust will kill low end performance. To small diameter exhaust will have a high velocity but will not be able to keep up with flow and will kill top end performance. The key is finding a balance between the two.

Chris

 

Well on the 07 it seems test pipes work great in these dynos AAM posted. I just hope that together with the HKS knockoff I get some good results.

 

Back pressure is always a bad thing. Period. Increased exhaust velocity increases the scavaging effect and promotes a more effecient exhaust system. But as Hypersprite mentioned, balance is key.