ClubCJ - The CJ Lancer Club

Basically what voids your warranty is, anything you add that directly affects/causes the problem of another malfunctioning part.
For example, you decide to fit a 500shot of NOS, as a result, you get rev happy and blow the engine, this is not covered in your warranty.

Spring change - if your shocks break, warranty isn't covered, as the springs are "part" of the shocks performance.

coils - suspension warranty N/A, as your not using it anymore. Brakes, should be a different story, as they are not "directly" (as said by Mitsubishi) affecting the brakes.
Thanks to Phoenix for all his knowledge.

please feel free to add more info.

They can void your warranty if the person servicing your car is having a bad day. But on the other hand look at my mods and I go into the dealer every 3000 miles and no warranty problems yet. But legally they can only void your warranty if the after market part in question is the direct cause of the problem