Computor chips air filter, go with K&N
And Super chargers or turbo chargers if you realy need to go faster.
I got a 07 Mustang GT and go to car club meets and thats what alot of them are doing.
I didn't But my wife drives it so I don't need 5 or 6 hundred in HP.
Here is some photo's of mine on this site below.
Kurt

http://www.flickr.com/photos/kurtvara/page6/