They can make some pretty circuitous excuses if the system that fails is in any way related to the system you modded though. I wouldn't be above getting something in writing from Joe Mitsubishiguy stating that whatever mod you asked him about will not void your warranty.
Whether Mitsubishi is going to be around to fix anything by the time your warranty expires is another issue.
What else did you look at before buying this thing? Why'd you pick it over any of those? I'm just asking because
this is the only thing I've read about that car so far, and it isn't exactly encouraging.