Re: Question about Supercharger and H/C
Installing a blower ontop of an LS1 with 10.8:1 compression is probably not a great idea. You might want to check around with some of the more experienced members, but I understand that thicker head gaskets is not recommended either. The best way to lower compression is through bigger heads (i.e. 6.0L heads) or piston work. For our engines, the stock (10.1:1) compression is already pushing it. 9.5:1 would be even better, for say 10+ PSI. I don't think thicker head gaskests will drop you enough to be in the "safe" zone, and therefore you'll be severely limited in terms of how much boost you can run safely.
If you already have milled heads, why not consider a bigger cam (224 or 230, 112LSA) and using nitrous (125 - 150 shot). You'll go a lot faster than with a blower, given your high compression, and your motor will probably last longer, since you won't be on high compression AND boost all the time.