I wanted to get a few opinions as far as my exhaust was concerned. Currently I have a FP Big T28 with all supporting mods. DNP SS tubular exhaust manifold, SS tubular atmospheric dump O2 sensor housing, 2.5 inch Buschur racing SS downpipe, 2.5 inch Buschur racing hiflo cat and 3 inch Thermal research cat back exhaust. I'm not planning on pushing this turbo past 22 psi. A friend of mine was thinking I could get some gains (maybe significant) from going to a full 3 inch downpipe and eliminating the cat. I'm looking for some feedback. I think at the least I'm going to do a test pipe instead of the hi flo cat.

Go with the full three inch piping. You'll thank me later.

Also check out post #220 in the thread below (on page 8).

http://www.dsmtuners.com/forums/new...tter-2-5-vs-3-exhaust-discussions-merged.html

3" ftw. I assume emission testing is not an issue in Wisconsin? If so, get a 3" high flow cat.

I wouldn't mind if the Talon sounded a little meaner. dang it all if the front section of the Thermal research exhaust doesn't neck down to 2.5 inches. If I went full 3 inch I'd have to cut that section off. Any downpipes that you guys would recommend to accomplish this? Did I see some sort of band clamp fitting that goes around instead of a flange?

Just take it to a trusted performance shop and have them replace that 6 inch section of piping. I also have the Thermal system, and it's exactly what I did. Definitely happy I took the time to do so. Mates up to my RRE DP very nicely.

bmoha2 said:

I wouldn't mind if the Talon sounded a little meaner. dang it all if the front section of the Thermal research exhaust doesn't neck down to 2.5 inches. If I went full 3 inch I'd have to cut that section off. Any downpipes that you guys would recommend to accomplish this? Did I see some sort of band clamp fitting that goes around instead of a flange?

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I have a Thermal catback with the neckdown cut off. I use band clamps too, they are available at jegs among other places. I use a 3" MR downpipe.

When you cut off the neck-down you'll have to make up the length difference. Get a downpipe that eliminates the cat with no neck-down at the end. Then you'll have a short length of space between the two pipes. In this gap I cut off a little additional pipe and installed a high-flow cat. Optionally, I have a 3" resonator that is the same size and length for track events. The cat has a clamp at either end that removes easily to be replaced with the resonator. The resonator is a straight through design, Magnaflow I think. With this particular orientation, there is little restriction but the sound is very reasonable. See sound clip..

By the way, the FP T28 turns into a little beast jumping from the typical 15psi to 20+psi. The torque hit gets pretty insane, it's awesome. Robert at FP told me (on the Big T28) "It runs very well in the midrange at 25psi." I wouldn't know, I only ran 24psi.

Clip: YouTube - DSM Thermal exhaust 2step

Technically exhaust doesn't really matter much because with turbo cars you don't need back pressure, BUT a bigger exhaust means more air flow for your turbo. It will defenitly help on the spool. I personally have never experienced the difference from 2.5 to 3" , but i did notice a difference from stock dp to 3'' apexi dp. The turbo spooled better and quicker. So yeah go with the 3", and btw thermal r&d is the shit i have it and love it.

The big gains will come from removing the cat. The power gains from a 3" DP at your power level will be minimal.

more food for thought What kind of opinion of do guys have of the Megan downpipes>? I'd like to stick with a Buschur racing 3 inch SS downpipe but man are they expensive

I see piping as piping, my megan downpipe works like any other piece of 3" tubing. Sure, it's a slight pain to install with the 2.75" inlet, but not prohibitively so. Flex sections seem to differ though. You can't go wrong with a quality vendor downpipe and I'm for always buying the best quality parts you can afford.

Personally, I agree with replacing just the cat (with straight pipe) per CanadianTSi's advice. Remember, you're dumping part of the exhaust to begin with.

I would recommend RRE's short downpipe and their test pipe. I run their long downpipe on my car.

^ Me too.

CanadianTSi said:

The big gains will come from removing the cat.

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Some gain, but not big gain. Maybe 5 -10 wheel HP at the very most.

Definately go with a full 3 inch.