I cant believe I'm gonna even touch this one...
zeromain?id=173
Engine forums, use them.
Also, asking "which is better" is a real bad idea. People will tell you that the one they have/like is "better" by default of human nature.
here are the lowdowns..
Potential Power (least to greatest)SR -> KA-T - >RB
Installation work (LTG)SR -> RB -> KA-T
Ease of installationSR -> KA-T -> RB
SizeSR -> KA-T -> RB
PriceRB costs a hell of a lot more,
SR and KA-T are debatable depending on how extensive you get with KA-T
Disclaimer: These are only my opinions and estimates, dont take my word for it, do your own research. I am not responsible if you F- up your car or make a decision you later regret.