Welcome to the boards!
Have you switched over to synthetic motor oil yet? It'd probably be a good idea as the 2.7L V6 has oil sludge issues. At the same time, you could put in some real low-viscosity oil.
Anyway, on the aerodynamics front you're car is pretty good, but there's always plenty of room for improvement
There are a few mods that would be fairly easy, low (visual) impact, and cheap, like wheel spoilers, grille-block, belly-pan, that kind of thing.