Mods
I agree with RAMINSPEED on this one it's going to depend on the dealer, some will work with you an some will work aganist you on mods. I considered the replacement of my stock front coils to ones that raised a couple inches more,but was afraid to mess with front end since it tracks so good. Instead opted for Matt400 mod of removing the rear spacers to give a more leveled out look. You can still run a larger tire I believe, check out Matt400 Readers Rig for info on the tires. I myself am pretty well sticking to stock condition on my truck, but you may have plans for something more radical with yours.
Good Luck with your Mods.
Tony