I also have a 06 ZX3 with just a few mods, but it looks great. Definitely looks a lot better with window tint. Allowed on back window and rear side windows, but typically not allowed on front side windows, nor windshield. However, you can get a lower tint for the front side windows (like say 40% for fronts and 80% for rears), and this way it won't look so noticeable that they are tinted. You can still see inside, but it looks way nicer than the super-clear factory windows.
Also, I bought a set of used SVT 5-spoke wheels, and wow... it looks like a totally different car. Strongly recommend aftermarket (or SVT) wheels to give your car a nicer look.