will this raise or lower my compression?

and is there any power added for doing this?

 

the only advatage you would be getting is a 2" intake valve.. you will loose power due to dropping your compression, plus they dont flow any better than 862's

 

well a local guy wants to trade me. he says he will even pay for mine to be ported ( the ls1 heads) then should i just ahve him mill them and and raise the compression?

how much can i mill be for i need to fly cut the pistons?

thanks for the quick answer by the way

 

well by my calculations you'd have to mill them down about .035" just to match your compression ratio... i personally wouldn't mill much more than that, then u start having to worry about your intake lining up and PTV clearance... really not worth the hassle for me, but to each there own..