Wouldn't putting lowering springs, side skirts, exhaust, spoiler, etc. ruin the "sleeper" aspect of your car, aside from the rims and painted capilers? Don't get me wrong, your car is awesome, but it won't be much of a "sleeper" any longer.
Aiwa flip down head unit
Pioneer 6x8 3-ways all around
Two Polk/Momo 10" subs pushed by a bazooka amp
Custom grille
Silverstar high/low beams
Autolite 8mm plug wires
