i am wondering about want kind of modifacations i can make to a new car that will not interfer with any sort of warrenty. i havent bought a car yet. im mainly worriered about the h/u etc.

Call the dealership and find out

I have a Scion tC and Toyota's warranty goes like this-

U can do and install ANYTHING you want to on your vehicle.

However, if you ever need to go in for service for something, if something you have done or installed is the cause of the problem you may be having with your car, then it will not be fixed for free.

Your warranty is not void, it's just void per service date.

You could install a turbocharger on your car if you wanted to.

If the ecu malfunctioned, as long as a piggyback or ECM had nothing to do with it, then you are fine...Although if you have an ECM,hehe, your whole electronic system would probably be void permanently...but that's an assumption in that scenario.

The do have to prove that what you added was the problem though. And sometimes, that's pretty hard to do.