Hi, first of all, i'm sorry for bad english.

I bought a 2001 sunfire turboed a few years ago and the engine broke down, but the problem is not that. I bought a 1998 sunfire with the same engine.
My 2001 sunfire has a wallbro 255lph pump, an act stage4 clutch, and many other things, but before transferring my setup, I'm stuck on the issue of timing and the ECU.

I read at some place, the 2001 ECU don't fit in my 1998 car, and I can't see in any place, which Mods I need to do in the ECU to run my car with a turbo. Did I really need to mods something in the ECU ? and the timing, what I need to do ? I know its probaly to retard it, but How ?
The last owner of my 2001 sunfire has changed the gapping on the spark plug. Why ?