Take a look at this page Carl -

http://www.sema.org/main/semaorghome.aspx?ID=50096

It's a good page that explains what your rights are in your limited warranty and how you are covered by the Magnuson-Moss Warranty Act. In general, things such as exhaust and cold air intakes will not void your warranty. But, when you start upping the boost on turbos, changing transmission shift points, and adding chips/tuners you get into a shaky area.

Many Ford dealers will not warranty trucks with these upgrades because it is so easy to vent your block if you go too far.

I've run into this several times with my Lightning here in Austin. Covert Ford took one look under the hood at my cold air intake and said they would not perform any warranty work on the truck. I took the truck to Leif Johnson after that and they had no problems with any of my mods.

You may want to look around on some of the performance message boards before you decide to mod and read some of the stories regarding Ford denying warranties on their performance vehicles. Remember, you've have to pay to play.

Good luck with it.

--Jeff