Check out the dyno for the DP/Race Pipe:
http://www.atpturbo.com/turbopiping/monstermate/images/neonsrt/StageIINeoDyno.jpg
That is a gain of 18 HP and an
INSANE 57 lb/ft of Torque. Maybe it is just me but for $300 that seems like the most Power for the $....
The only problem here is that if you get the Race Pipe it is kinda illegal in most states. But here in IN you never have your exh. checked so unless a cop slides under your car to look for a Cat I think you will be OK....
BTW, if you do get caught with no CAT the fine is like $20K or the price of another SRT-4...
If you want to play it safe you can get one with a cat for a gain of 15 HP and 41 lb/ft of Torque. But that will cost you a few extra bucks. I am willing to take the chance of a Cop crawling his ass under my car to make sure my Exhaust is up to code. So far I have never seen a cop actually do it but I have heard stories.
If you have any more questions check out ATP's website. That is where I got all my Info:
www.atpturbo.com