My #1 recommendation for your truck is the LED tails. IMHO, the old style tail lenses are about the ugliest lenses ever put on a vehicle. Your truck looks nice, but it would look much nicer with the updated tail lenses.
Exhaust would be my #2 recommendation, although it doesn't have to be a Gibson. The Gibson sounds good though. Give me about a week and I'll see if I can record a sound file for you. PM me if you haven't seen a reply with it by this time next week.
#3 recommendation would be nicer wheels.
If you're going to go to all the trouble of a spacer lit, you may as well do the whole lift, not just level, IMO.
loner