[19bonestock88]

Ditch the cats? Got it... There isn't a smog pump on my car, so that's not an issue, and EGR helps with mileage as far as I'm aware(correct me if I'm wrong)... I'm not sure how much the head could be milled for compression before cam timing becomes a problem... If I built from a bare block, I could order pistons as high as 12:1 compression, but finding fuel could be problematic... I don't really wanna spend $1-2k building this engine(think ROI) when a good shape LE5 long block could be had for ~$300 and I could get a free L61 head to work and build the LE61(hybrid) while I'm still driving my car...

Of course, the gained efficiency of running high compression(11:1) would have to offset the additional ~20% cost of running premium fuel that it would likely require...