i have the berk test pipe on right now and just got my T1R 70 system. the system includes the test pipe and today somone mentioned that the berk test pipe is narrower in diameter than the 70mm system and therefore i will lose power...is this true? i really would rather keep the berk pipe because of the CEL issue., i also added the stock heat shield on it too and want to keep that as well....let me know thanks,.

 

a smaller diameter test pipe will hurt the top end.

 

i assume the header to test pipe connection will fit a stock or aftermarket header fine either way, im just wondering if the testpipe to resonator connection is smaller and therefor i will lose flow, 2.5" is 63mm so is the berk test pipe 7mm narrower than the T1R system? thanks.

 

Yes, the T1R is 70mm including the test pipe that comes with it. Just buy the T1R and sell your Berk. The T1R also comes with the drilled out connector for your O2 sensor. I've had mine in for 3 weeks and not one CEL.

 

i already have the T1r system. The reason i want to keep the berk pipe on is because i want to keep te CEL off and i dont want to deal with the spark plug defouler mod to keep the light off. I also have the stock heat shield mounted to the berk pipe so it looks stock. if i understand correctly the stock header outlet is 65mm, the berk pipe is 65mm then the T1R resonator part back is 70mm, so im actually not losing any flow because the header to cat connection is the same and once the exhaust gas passes the berk cat it goes into the 70mm pipe. the 18" or so that the pipe is 5mm narrower really dosent matter because its just like having a longer header correct? let me know if theres anything im overlooking.

 

I'd actually be interested in seeing a dyno of a complete header back T1R exhaust. I'd suspect any top end gains would be negated by mid range tq lose due to lower backpressure. Aren't 70mm applications more suited for FI use?

 

FYI backpressure is always bad. The people who claim that backpressure helps power don't have a clue what they are talking about. Going to too large of an exhaust diameter can hurt power but it is not due to a lack of backpressure. Instead it is due to a decrease in exhaust velocity. Larger tubes generally decrease exhaust velocity. High exhaust velocity will help with scavenging from both the header and cylinders. Lower the exhaust velocity too much and you'll affect scavenging. This is what affects power NOT backpressure. Backpressure is always bad, and high velocity tends to always be good. The ideal exhaust is a balance to achieve minimum backpressure and maximum exhaust velocity.

 

Thanks for the clarification.

 

so the smaller berk pipe coming from the header would be benificial because it will allow the gasses to be flowing at a higher speed for a longer period of time before the gasses are slowed down by the resonator as well as the 70mm system? thanks for the information, CrazyPhuD very interesting to read how everything actually works.
CHRIS

 

By your logic then, the restriction at the SMALLEST diameter anywhere in the car would be the maximum effect you can create. This just isn't true, however. The 70mm ones have been dyno tested and make the most power for NA. For FI, 70mm isn't enough. 70mm is roughly 2.75 inches, and you generally want at least 3 inches for FI. Just drill out the damn foulers and be done with it You bought the exhaust for power, so make the most out of it.