Ok as a former chiptuner and a guy who had a car wih 4x as much power let me explain this to you. The Moss-Magnusson warrenty act only pertains to replacement parts that meet or exceed manufacturers specs. Now with that being said things like Air filters and such as longs as they filter as well as the OEM.
HOWEVER, do you really think a warranty should cover rods, pistons, blocks that will be taking 100+ more HP and probably 200ft/lbs of torque more then the factory truck? They can void the powertrain warranty, but can not however void warranty on things like switches which will not see an increase in stress due to the intsall of the turbo kit.