I work for a dealership and know what the ratings are for the stock internals for both the GT and the GT500.
What I dont know is if you put a Saleen or Roush blower on a 4.6 GT mustang ... what is the hp rating for the internals before you start taking chances that things are going to blow up
the internals dont change when you bolt something on. unless you upgrade the parts inside your motor, there is zero difference between a N/A car and one with boost. the difference is the tune. with a power adder, you are more likely to cause serious damage from detonation.