will after market spring affect the warranty?

[slvryaris]

http://en.wikipedia.org/wiki/Magnuson-Moss_Warranty_Act

THis states that a warranty is only violated if the change you made voids it. Add a turbo and blow up the engine and show proof the turbo was to blame then the warranty for that repair is void. Add an exhaust and your suspension goes out your fine. The only way they cannot cover something is if something you added is the cause of the damage.