whats the difference in hp gains between a 3" turbo back exhaust with the cat and without it...i would like to get exhaust but with mitsubishi being the way they are with warranty id like to keep my cat. But id also like to gain a little more than just sound

 

If you keep your cat, then you won't have a TBE, you will have a cat-back. That's about 15-20whp less than a catless TBE.

 

what about a tbe with hi flo cat vs. tbe with testpipe.. pretty big HP difference?

 

10whp probably, maybe 15. A HFC doesn't do much for you.

 

The only thing a hfc would be good for is if you're environment-conscious as well as wanting to pass emissions. Other than that, it's ~10-15whp increase if you switch it out w/a testpipe

 

I have a HFC.
It makes a good WHP from stock turbo compared to stock cat. I haven't used test pipe yet but I heard there is a 2~8 whp difference between test pipe and HFC if you are on stock turbo. not much you can feel...
But if you have a bigger turbo HFC will make you lose a lot of power.

 

I am pretty confident that a catback, DP or both won't add anything until you replace the cat with a high flow or delete. Think of the cat as a pressure restrictor

 

My Greddy TI Titanium with a cat delete gave me 10-15whp.

 

yeah sounds good, but the problem i forsee is that when i take it for emissions, they use a mirror to look under the car... then what?

how do u guys get through emissions?

 

i was talking downpipe then cat then 3" for the rest a catback wouldnt have the downpipe



 

Simple. Put on your cat before going to emission. Total 4 bolds.

 

+1

Cali folks, use caution. Rumor has it that CHP is using mirrors to check for cars with no cats. Automatic tow.

 

That takes care of the inspection. But how about daily driving? How do I get rid of that smoke coming out of my tailpipe. And that horrible stench? How do I get rid of that?

 

There should be no smoke. I don't know about a stench, but the fumes are a bit annoying. Is that what you mean by a stench? I think of a stench as the smell of a burned clutch or my dog's poo, not the standard exhaust fumes you smell from a catless exhaust.

 

Here are a few options to consider:
1. Muffler replaced (~5HP gain after turbo spools up, no difference in spool over stock)
2. Catback replaced (~10HP gain after turbo spools up, no difference in spool over stock)
3. Down pipe and Catback replaced stock cat in place (~20HP gain with quicker spool, downpipe helps a lot)
4. Downpipe, Cat and Catback replaced with HFC or test pipe (dump back exhaust) (~25HP gain with quicker spool)
5. O2 Housing, Downpipe, Cat and Catback replaced with HFC or testpipe (true turbo back exhaust as it replaces everything behind the turbo. (~35HP gain with quicker spool)
6. 9.8-10.5 housing, O2, Downpipe, Cat and Catback replaced (only if you are pre-05 models) ... it is more than a TBE because it replaces part of the turbo. (~45HP gain with quicker spool)

(remember most HP nos. are approximations, it will vary by exhaust design and manufacturer)

Tests have shown that a test pipe only adds 5-8HP over a HFC, if you have a random tech HFC there is no difference in power between it and test pipe ...