With 12.5:1 you will not be able to drive on pump gas iirc. You may be able to pull some timing out of it with msns but out will negate the benefit of going with that high of compression. Now if you run e85 or race gas all the time then by all means do it. I say go for it but just wanted you to knew that 12.5:1 is a little too high for the street imo.