Cost: $800
Time: 15 minutes
Theory: Not only do they look sweet, but the larger wheels allow for a wider tire with a smaller profile (sidewall) so there is increased traction and less sidewall flex.
Opinion: With stock tires, taking a corner quickly gives the feeling that the tires are going to roll over on themselves. The aftermarket wheels and tires (Falken FK-451's) make an incredible difference that just begs for a suspension upgrade.