There is actually a federal law covering the modification of vehicles.
The Magnuson-Moss Warranty Act (P.L. 93-637) is a United States federal law (15 U.S.C. § 2301 et seq.). Enacted in 1975, it is the federal statute that governs warranties on consumer products.
If I remember how it was explained to me the manufacturer can only deny you warranty coverage if they can proove the damage was directly caused by the aftermarket products.
So for example if your crank shaft bearings go out at 2000 miles, unless they can proove that it was somehow due to you not running baffles in your pipes, they have to cover it.
The Magnuson-Moss Warranty Act (P.L. 93-637) is a United States federal law (15 U.S.C. § 2301 et seq.). Enacted in 1975, it is the federal statute that governs warranties on consumer products.
If I remember how it was explained to me the manufacturer can only deny you warranty coverage if they can proove the damage was directly caused by the aftermarket products.
So for example if your crank shaft bearings go out at 2000 miles, unless they can proove that it was somehow due to you not running baffles in your pipes, they have to cover it.