An d also keep in mind with timing, more isn't always better(espescially with the ATT). GM tuned for emissions first, and reliability 2nd. For lighting a turbo off, go into your spool up areas of the timing table and retard it back a few degrees to help with spoolup. By retarding your timing you put more heat through the exhaust and get a quicker spoolup. You need to map out where your cruise areas are as you will want to run advanced timing there for a milage tune, but with the bigger turbos you will want your spoo up areas to be slightly retarded to aid in spool. On the top end you normally want to go for a 50% timing figure, but without knowing the injection duration it is difficult to determine this amount. For people with a GM-X turbo(or still using the vacuum control), lower your boost down to a pound or less in your steady cruise areas for best milage(GM did this in there later tunes, and my updated BXPY PROM has it in it) then bring it back up once you come back into your power areas. I have some ideas in mind for some tuning changes, but until I find what I think is an accurate .XDF file I'm a bit leary to do much in one for somebody else(its one thing if I blow my own engine, it's a different story if one of my tunes hurts somebody elses ).
I'm glad someone that knows what they are doing has joined in, I'm just a Guy that got Google to work.