8.5 would be better suited for a turbo application where higher boost numbers can be made.

 

exactly... only running 12 psi, 9.5:1 isn't that high.... running 28 psi on a 9.5:1 would be high... that's why that rebuild of 300hp someone posted they actually raised the compression up to 10.5:1 it won't make that much of a difference on a roots blower, a turbo on the other hand it would

 

high compression will give u much better low end rather then low compression pistons, the engine will be very laggy till boost kicks in to start pushing that beast!