Start here: airram.com

You can change the gears. Is your 5sp a manual or auto? Cylinder head work is always good, so are cams. HO cams seem to be made of gold, but I've heard the 2008+ 4.7 cams seem to do well as well. Possible to maybe adapt the 08 heads to your block as well. The 08+ intake manifold can be used for perf gains. Over on DT (dunno if he posted it here) a dude with a 2002 4.7 adapted and is in the midst of tuning with a supercharger on it. Even with a stock engine, custom tuning can net you more power.