Has anyone ever used the SLR Performance "piggy back" Power Chip? Looks like its an add on that works along side the oem chip, adjusting engine perf based on feedback from O2 sensors and other inputs. They make some pretty big claims about hp, mpg gains, changes in power band and so forth. :sign0144: Just drove it home today: 02 silverado 4wd, auto, G80 R diff 3:73, NP8 xfer. Anybody know what YD3 for the Ft axle means?