My first attempt in SPL in my Blazer was with a single 12" CVX on 750 watts with the sub and ports to the front, hit a 142.9 sealed at the dash and 143.5 outlaw at the kicks. I stepped it up last season with a pair of 10's and made it subs up, box sideways and ports to the driverside, and a bigger amp and hit a 149.2 on the floor sealed. In a Blazer you can reach a certain level with outlaw, then you start dropping your scores. It also helps to hold down the bottom of the rear glass, you lose air through vents in the rear.