turbo-back HFC or testpipe

[Scoped_GST]

So its probably about time for me to get a turbo-back setup installed on my car. Anyhow, I've been thinking of the possibilities, and I like the idea of a 2.5-3'' downpipe to a 3'' cat-back with HFC's (high flow cats). Some people say to just go with the O2 eliminator and srew the cats, or just go with a test pipe instead of the cats. I dont want to smell gas or exhaust all the time either, so what would probably be the most practical daily driver(plans for Evo III) setup?

[JoeWagon]

The only reason you should get a cat is if you are worried about being illegal, doing emissions.. etc. The way you worded it, you make it seem like an o2 eliminator eliminates the cat. They are two different things, but usually it DOES eliminate both, but always the o2 housing.

[kjewer1]

Also its singular "cat," not cats. At any rate, another reason to run a cat besides the obvious legality issue is sound. I'm tired of getting pulled over for the full 3". The cat does make the exhaust quieter and more mellow. But if it makes it quieter, its going to slow down spool and reduce HP a little bit. Back when I did some testing while using the 14b, a test pipe was worth 1.5 mph over a cat, or roughly 15 hp. On a turbo that small though there is really no spool up difference. The larger the turbo, the more the cat will affect spool and power.

[97_3clipse]

speaking of a turbo-back exhaust ..i plan to run a 14b very soon, and then eventually move to a evoIII... what do you guys think about the slowboy racing 2.5 turbo-back ?http://slowboyracing.com/more.php?id=1381&
or for $50 more sould i get the 3.0in turbo-back?
http://slowboyracing.com/more.php?id=1383&
and save my self money in the long run....

[JoeWagon]

Your choice. 2.5 inch can be fast, but $50 while you are buying exhaust isn't much for that upgrade.

[joemathews]

The difference between 2.5 and 3" is minimal, to a point. If you have big plans for the car as a track car in the future (run 11s or lower), you may want to go 3" to provide enough flow for the bigger turbos.

If I were you, my primary concern would be streetability. It sounds like you want a very streetable exhaust, in which case the 2.5 might make you less likely to get a ticket. If you go the track, you can always drop all or part of the exhaust to eliminate the 2.5" restriction, but I don't think it would impede flow significantly.

[Scoped_GST]

So right now im thinkin 2.5-3'' downpipe to a 3'' HFC then to a 3'' back to a Dynomax Superturbo muffler(looks very stock, but flows very well and not HUGE sound). Opinions?

[kjewer1]

The edlebrock RPM mufflers have been used successfully on DSMs. Not very loud, but still flow quite well. If I was going to build another exhaust to quiet my car down thats what I would do.