You should be fine unless your some how caused damages to you vehicle during installation or damages occurred as the result of the modifications. An example would be that you since you modified the springs your tires now wear down improperly. As a result the dealer is now not responsible for any tire wear issues because you had made changes to the suspension. Conversely, since you've only modified your suspension and nothing else, they can't turn you down for other warranty issues like if your radio were to stop working or your alternator quits.
Magnuson–Moss Warranty Act
http://en.wikipedia.org/wiki/Magnuson–Moss_Warranty_Act