Yeah, I've got a 5.3 and I'm gonna put in a 5.7 LS1. I've been looking at dyno graphs and dyno #s of LS1s w/ small cams (224/224 & smaller) and the under the curve torque and top-end horsepower are pretty dang impressive for only a .4Liter/21c.i. increase in displacement over the 5.3.