Well, right now SCT has the
XCalibrator II that flashes your EEC and improves power and driveability. It's $375. It also reads and deletes CEL codes and real-time analysis. All you do is find you compuer code and tell them your mods and plug n' play. You can also go back to stock.
It's definatley worth the money; not only can read codes (pays for itself right there), but it imporves fuel economy and power response. I think the average gain is around 15 RWHP. Alot of newer LS owners are getting them lately.
Only problem today is you'll have to use premium fuel; which as you know, is already expensive here. I'm paying $2.50 a gallon right now...