whats the size difference on the bore and how much power will i get on my integra, will it fit

 

there is no set amount of power you will gain from a s2k throttle body. The gains you will see depend on what you already have done to your car. It will probably be cheaper and more effective to bore your stock TB.

 

Yes, it will bolt right up. I've seen claims that the S2000 throttle body is pretty much the same as an ITR throttle body, however when holding them side by side, the S2000 looks a touch larger and has much thicker walls which would allow for you to have it bored even more. I agree with b18c1995, you'll find more power elsewhere unless you've already built the engine.