ShaneM

The roush blower is perfectly capable of giving you all the power the stock block can handle. You can get 450whp out of it with a pulley swap and a good tune, maybe the CAI roush makes. You will be fine. the intercooler kit on the 427r m90 is the same kit used for the Roush TVS blower so it will cool just fine. YOu will nee dsome sort of fuel systme upgrade for higher power though, BAP or GT500 system. teh roush cars only upgrade teh injectors, uses stock fuel pump.

LilRoush

03/04Cobra uses the M112, Roush uses an M90 on these. There are lots of upgrades to squeeze more power out of them, though. Roush offers the TVS blower upgrade as well (similar to what was standard on the 510 hp P-51A/B models in '08 and '09). That upgrade will put you far beyond what your STi was doing if you have the bottom end that can take the beating.

BurnsTACP

Ok here's some more questions. I have looked at Saleens a little too and the chick at the dealership said some stuff to try to steer me away from them. Said Saleen is going out of business, that 427Rs are more of an all around upgrade, and that all Saleen's cars are defective from Ford and they buy them and fix them to get a break on the purchase price. Is one really that much better than the other or are the about on par? I'm looking for what will be the best/funnest at an auto cross.

socalwrench

It's interesting that you're coming out of a STi. I drive the Mustang and my wife drives the WRX. Both are great cars. My Mustang is definitely faster, but that AWD system provides tons of traction during hard cornering.

BurnsTACP

My fiance is in love with mustangs and I am looking to lower my monthly payment but keep a fast car. Don't get me wrong, I LOVE my STi. It really moves. I just don't want to pay as much as I do per month to drive it. The 427R will be cheaper on my insurance too.