I've got window tint and Stillen exhaust. I don't see myself doing anything else to the car.
I might redo the stereo at some point, but it's the only part of the car I'm not totally 100% satisfied with.
I got the Sport and Touring packages, so the things I don't like about the base model (18 inch wheels, no wing, econocar looking brake calipers, cloth seats) came properly done from the factory
I don't really care if my Z doesn't look unique, as I rarely see 370's on the road and it's just a daily driver. If the Z ceases to be fun for me, I'll buy another car.