Here is some warranty stuff i cut and pasted.
Based on the Magnusson-Moss act
No aftermarket part or accessory that is properly installed on your vehicle will entirely void your original vehicle manufacturers warranty. According to the provisions in the Magnuson-Moss Warranty - Federal Trade Commission Improvement Act, It is the dealership's responsibility to prove that your modification directly caused or affected the failure you are trying to resolve. With that said, some dealerships are more performance-oriented than others and are more willing to work with customers.
Warranty-related materials, published by the new vehicle manufacturers, state that the installation of aftermarket parts have no effect on the warranty unless such equipment causes the problem that leads to the warranty claim. Nonetheless, some dealers have improperly denied warranty claims even though the claim had nothing to do with aftermarket parts. I.E., just because you install an exhaust system, your suspension failure warranty claim cannot be denied. If you experience a problem with an uncooperative dealership, point out the provisions of the this "FEDERAL ACT".
For more information call your vehicle manufacturer or click on the link to go directly to the Federal Trade Commission's website to find out more about this law.
You can do a search and get more info. But if you mention the act to the service manager I am sure you will hear their opinion change to "Your warranty is voided if the modification is the cause of the issue up for warranty." Or something along those lines.
Here is what you have to use if the dealer starts to get froggy when you bring in your fj for warranty work. They will not warranty the aftermarket parts but they have to be able to prove that the aftermarket part caused the toyota part to fail. So don't just be sucked into the dealer's way of selling you a part that is covered.
CAN AN AUTOMOTIVE DEALERSHIP VOID YOUR WARRANTY?
Your rights are protected through the Magnuson-Moss Warranty Act, 15 USC, 2302, and the Clean Air Act, 42 USA § 7541.
You have the right to buy high-quality, reliable aftermarket performance and replacement parts – an affordable and convenient alternative to the vehicle maker’s parts.
You have the right to use high-quality aftermarket parts and know that your new car warranty claims will be honored. In fact, your vehicle dealer may not reject a warranty claim simply because an aftermarket product is present. A warranty denial in such circumstances may be proper only if the aftermarket part caused the failure being claimed.
You have the right to patronize independent retail stores for vehicle parts and installation.
If a dealership denies a warranty claim and you think the claim falls under the rules explained above concerning the clean air act (such as an emission part failure), obtain a written explanation of the dealer’s refusal.
If you would like further information on what to do and who to call if your new car warranty is denied, call the Federal Trade Commission at 202-326-3128.