What are typical hp/torque gains on a plain off-road h-pipe on a bone stock Cobra? Is there any dyno pulls to prove that there is significant gains from just a cat-less mid-pipe?
In any event, try searching. There is an abundance of information about X/H-pipes, I gaurentee you will find the answer to all your questions. If not, I will give you a free American thunder catback.
I'd expect to see 9-11rwhp with a catless H. X-pipes are supposed to be superior for flow, and will yeild superior numbers on the dyno, but I guess it's all debatable. I can tell you that I can honestly feel a difference in power with my o/r X vs. stock. 4000+rpm I can feel that extra burst of power...you can feel it in your gut. I feel like I picked up at least ~14rwhp/tq past 4k.