Mods and Warranty
Ok, so as per the all too famous Magnuson Moss Warranty Act from back in the 70s: Mods do not in themselves void the warranty. However, say a part associated to the mod fails; if the manufacturer can prove there is a relationship between the two, they are allowed to void warranty on that part of the car.
For example, if you put some blacklines on your car and the next day the engine drops out of the car, the manufacturer would have to prove the blacklines had a direct effect to make the engine fall out of the car. If they cannot prove that, then your warranty is still intact.
On the flipside, if you add some engine modifications or engine management modifications and the engine explodes, then the manufacturer would have a valid case to void your engine warranty.
The loophole to this is if the new vehicle warranty specifically and clearly states that the addition of a certain mod will void the warranty ahead of time, then they can void it sight unseen.
In the end there is a balance, for any mod you addon, you must be aware that you are risking that portion of the car and therefore its not the manufacturers responsibility to warranty that part of the car you've decided to change. But this act does limit greedy/shady manufacturers from coping out of their responsibilities for the unmodified parts of the car.
I will attach the entire act below.