1990 Ford F-150 300 in-line 6 enginge and performance mods

Been looking around the internet for performance mods for the tried and true ford 300 in-line 6 cylinder.  Found a set of exhaust headers that will work, am wondering if any one else knows of some goodies that I can do to it to give it that extra umph.  She is fuel injected with a 5 speed tranny, and already has a cold air intake, but I know there is more out there, just a matter of finding it.  Any help would be greatly appreciated.