Seth, first off i want to apologize for saying 'lmao' on that one thing. I'd had a few that night though its no excuse. Partaking in a few tonight as well. Nonetheless welcome man. It's been a few years for me, but i since got back on this site about a month ago and plan to stay. Knowledge is key to learning and none of us on this site could say we don't continually learn or learn from others everyday because everyone's got their skill set and then those areas they're not as knowledgeable in. I will speak a bit on the SCR. First off G727ed has shot you some great info. I got tickled in his one post when he said he was running that high CR on iron heads but 'kept watch on things.' What he meant, imo, was he had a helluva tune on that motor to run that CR on iron. He paid attention to cooling, timing, type of pistons he was running, etc. IMO, to be safe with minimal tune, you are good at running aluminum heads at about 10:1. This build i'm doing right now, for street, 10:1:1. My goal is 93 non-ethanol gas and i think i'm within that realm with aluminum--at least both me and Brodix think so. Yes i will dumb my timing a hair among other thins. Yes SCR gives you more power (or bang as i like to say since it bangs those pistons down with authority, thus madly turning that crank, turning that fly/flex, turning that tranny, turning that drive shaft, and turning those rear gears). Serious Guy will always as G72Zed said want to run as high CR as he can within the scope of whatever application he's running. For street--me--9:5:1 on iron, up to 10:5:1 on aluminum--both with good tunes.