Send me your email and I'll send you over some pics before the kit and after. It made a huge difference in the appearance of the truck. Also, I have some pics on my profile page with 285/65/20's which I think made the truck look even better again.
As far as warranty, it shouldn't affect it. It could however if you tear out a CV joint caused by the kit, they may not replace that under warranty...that would depend on dealer I think. Mine says they love what I've done with it and have completed warranty work with no questions at all. That's all I know about that, the rest would just be speculation.