The on3 kit still don't come with fuel system upgrades, or tuning. So you can count on another grand for that.
If your good with a welder, Google "homegrown boost"

 

What you ought to be worried about, is your 4L60E.

 

Yeah, if you are going to beat on it the tranny will suffer. Mine made it over 50k miles before it started slipping on the 1-2 shift. But I am not too hard on mine.

Of course, then I started getting smaller and smaller pullies and more damage followed.....all to the tranny.