big horsepower gains from 9.6 to 10 are rubbish. maybe 2% difference at very best. I've been thru this on stock or near stock engines. BB mopar's had awful combustion chambers. if using pump gas your much better off dropping the compression and using more timing than raising compression and backing the timing off. reconfiguring the combustion chamber with a quench dome piston is best. if that can't be done stay around 9:1 and let some head mods more than make up for any power loss.