Originally Posted by PenguinGT

With a safe tune and GT500 fuel pumps, you should be fine. Keep it on the richer side of things and rest easy.

Originally Posted by shaun_beauchamp

Roush and the Ford Racing units seem to go to about 435 Hp and offer a warranty. So that's a sign that they don't plan for issues. I would figure a good figure would be that benchmark + whatever you are willing to risk. Mind you, if you make 800 Hp and you only get 350 to the ground, you aren't making your car "faster".

If you just want a "number" for the sake of saying your car has "so much horsepower" than you probably won't use half of that on the street. If you are going to USE the power, first set the car up for traction and then build a kit for max boost on the stock motor internals. You can move your redline down and use a conservative pulley. As you figure out how to lay down the power, change the pulley and keep moving the rev limiter.

If you're in the 460 Hp to the ground at 6500 rpm on stock internals, then you're probably near what the motor can handle. If you detonate with a bad tune...game over.

So, NA and beating your pony isn't such a bad situation. You can run in the upper 12s with a decent NA setup and have a great handling car. You can get into the 11s with a blown car on stock internals. You have to decide what the cost and reliability is worth.