Check out Justin @ VMP Tuning he is a Roush guru.

 

Roush is pretty convervative with their tunes.

I remember I went to a Roush sponsored car show and dyno-day back in 2006 with some friends that all had Mustangs and I had a GTO. My friend brought his modded '05 GT and it laid down just under 300rwhp If I recall. Roush had brought out a ton of their modded cars. All the 427R's were putting down 360-380 at the wheels at the most.



Then I strapped my N/A GTO down and laid down 410rwhp. The Ford folk were not happy to be shown up by my ugly Pontiac. I still would have rather had the better looking Mustang.

Proper tune and proper fully and your car will sing.