[rancherochido]

Well I finally got my S/C tuned and dialed in. Im at 420 at the wheels and feel preety good about being at a level that wont break much if anything (knock on wood). The question is... what exactly needs to be upgraded before I can move up to a more serious level of boost and what is a realistic limit without replacing the block. My tuner was talking about a "built motor" on some other apps with higher boost, what exactly was he talking about... forged internals??? The clutch and drive shaft are a gimme but what about the rest of the rear end. I know this is a really loaded question but any leads would be helpfull.

[GTRaptor]

I would risk going above 420 without at least an upgrade to forged pistons, it could well survive stock with more boost but there is always a risk.

Above 500HP and you will also need a forged crank and rods.

The rear end, primarily the axles are the weak point, more so if you will use slicks or drag radials.

[BlueStreak03]

I would not go any higher without Forged pistons and connecting rods. I've heard in several places that the stock GT cranks are good for about 700 or so, but you still don't want to wind that crank up past 6000 RPM or so with those power and boost levels.