Any part that rotates is much more important to lighten. And the farther that part is from it's axis, the more important. EX: It's much more important to lighten the tires than it is the lug nuts because the tires are the furthest from the axle. Dead weight on the car takes horse power to move forward. Weight that spins needs horse power to move forward AND to get spining. That said, lighten the flywheel, tires, wheels. I heard of a guy taking off the bumpers under the bumper covers to save weight. That doesn't sound to smart to me. If you're keeping the A/C and PS, you obviously aren't going to be going pro soon. Don't sweat a few pounds here or there. You will only notice it in your mind. If you strip your car, it will all ad up to quite an amount. But if you pick up a door pannel or a fender, you'll notice it doesn't weigh that much. Neither does the carpet. A Civic EX has lots of gear on it and is a lot heavier than a car like my VX that has nothing on it to start with.