HI,
Why would putting a Stealth Box (which means a subwoofer box you can't even see) in your car void ANY warranty at all. If that were the case it wouldn't be worth it to buy a Mazda. I did a whole box with two twelves in the wheel well of my Mazda 3, did a custom amp rack right behind the rear seats with plexi glass and three amps, customized my dashboard with an alpine 3342 EQ where the airbaig light and the cigarrete lighter used to be, and ran 0 guage wire back to my amps. IT LOOKS SWEET. I took it back to the dealer and showed it to them, not only did it not void the warranty, they were so happy they wanted to show the car in the showroom for the weekend and gave me a free MP3 player upgrade for my car. Nothing that you do to your interior can void the warranty of your car except to the modified part (interiors don't have a real warranty anyway because of the wear and tear factor). If you rip the fabric of your seats, just because it's a new car dosen't mean your getting a new seat.