Every motor has blow by to some degree. I know of no significant differences between the LS head and the B20 head. Supercharged engines respond imediately and generally are more reliable because the boost levels are determined by a pulley so you can't get crazy with the boost like you can with a turbo. If real power is your ultimate goal then turbo charging is the answer hands down. But personally I have always wanted to tweak a supercharged car to the limit to see what it can do. Luckily I will get that chance with my cousins RSX since he will be getting the JRSC for his car as soon as it's available. We will install it, and start with the 75 shot of NOS he already has and go from there. His block has been fortified for turbo duty so it should hold up to the nitrous we are going to throw at it. he is more into the show scene than he is racing but he wants to at least be able to beat up on some WS6's and the suprcharger should take care of that and then some. We're gonna shoot for low 13's. Oh, and the displacement factor is a moot point. worry about that later, you can always stroke it. Besides, I know plenty of people making tons of HP without the extra displacement.