NO. Most vehicle owners are protected by federal law: the Magnuson-Moss Warranty-Federal Trade Commission Improvement Act of 1975. Under the Magnuson-Moss Act, aftermarket equipment which improves performance does not void a vehicle manufacturer’s original warranty, unless the warranty clearly and conspicuously states that aftermarket equipment voids the warranty. In other words, that means a dealer cannot wiggle out of his legal warranty obligation merely because you install aftermarket equipment. To find out if any aftermarket equipment voids your warranty, check the owner’s manual. It is likely under the heading “What is not covered”. Although the language seems negative, remember your vehicle manufacturer is simply saying he does not cover the aftermarket products themselves. He is not saying that the products would void the vehicle warranty. A dealer must prove-not just say-that aftermarket equipment caused the need for repairs before he can deny warranty coverage on that basis.