Well, it would be retarded to chip your stock comp. on an LS! If you want more power and wanna keep stock ish parts, go LS-V... Throw cams/gears, springs, retainers, ect... Make a quick little N/A car... All pricey though!
If you just have header and intake, throw a full exhaust on it. You can also do some cheaper internals on the LS then chip it and will give you a little bit.