jis487, very nice X3, love those tail light.
I'm a hardcore tuning guy, coming from VW tuning world. I plan to do some mods on my X3 also. I see that KW has some Coilovers for the X3, and i'll be looking at some OEM 19'' or 20'' wheels.
I'd like to find a CAI, but dont seem to find any, and will get a custom catback installed.
One thing might stop me from doing mechanical mods, is the warranty, I know Mini was VERY picky with aftermarket mods(if it was not John Cooper Works mods), so BMW is probably the same way.