How much HP does a 3 in down pipe add on a mildly tuned Evo?
I have a UR 3 inch Catback and was considering a down pipe before doing a ECU reflash such as Visnu's Xfash when it is available. Is the DP worth it in this case?

 

ALOT< ALOT of power, BIG difference. Get a 3.0 turbo back NO CAT. 30+WHP, maybe even more with tuning, and a TRUE topend, your turbo will love you for it, but make sure you have an Intake, better bov, MBC< and tuning before this mod.

 

It seems like the stock DP with no CAT would make more power than a 3in DP and high flow cat. True?

Like I said, I don't want to do a tone of mods. Just the exhaust and an Xede or Xflash. Shiv doesn't have any maps for a test pipe, so I need to road trip for a custom tune or do a better match of his tested mods. Which takes me to a DP decision. I figured I would loose some power by putting a cat back on but would get some of it back with the DP.

 

FWIW, I do have maps for test pipes. For both Stage Zero and now Stage 1. Even if I didn't, it wouldn't be the end of the world running a non-test pipe map with a test-pipe. The most you may have to do is dial back the boost map a bit to prevent overboost/spiking.

Cheers,
Shiv