I recently saw an extremely lifted Dodge Ram that had a license plate holder that read: "Yes, I have a small penis." I really wish I would have taken a picture.
On a serious note, some body kits were designed to ensure the same ride with the kit on. The suspension and all of that should work the same. If you're just adding the kit to increase your tire size, you should be just fine. Suspension kits are a lot more to invest in, and if you're not talking about making some trail rig, don't bother.