Dear Tom and Ray:

I am writing in response to a recent letter from the owner of a Dodge Dakota who wanted to add some performance parts to his vehicle: a K&N air filter, Flowmaster exhaust, performance chip, high-performance plugs, wires, cap and rotor. Your response was that if he added any of those parts it would void his warranty. Not only is that untrue, but it is illegal for a warranty to be voided just because an aftermarket part was added to the vehicle. I have enclosed sections of the federal Magnusson-Moss Warranty Act for your edification. -- Cathy

TOM: We have to stand by our advice, Cathy. The Magnusson-Moss Act says that a manufacturer may not deny warranty coverage solely because a customer has used an aftermarket part.

RAY: But if the manufacturer determines that the aftermarket part is in some way responsible for the mechanical problem, it absolutely CAN void the warranty. And many of the performance parts this guy wanted to install certainly could be blamed for future mechanical problems.

TOM: The Magnusson-Moss Act is meant to protect a guy who goes to the Poky Lube down the street and gets a Fram filter instead of a "genuine Dodge filter." In that case, the Dodge dealer can't refuse to fix the engine because the guy used another brand of filter that meets the exact same specifications.

RAY: But if a guy puts on a free-flow exhaust that lowers the exhaust system's back pressure, and then asks the dealer to fix his burnt valves under warranty, the dealer could certainly point to the modified exhaust system and refuse to cover it.

TOM: The same is true if a guy puts on a set of humongous wheels and then tries to make a warranty claim for worn-out wheel bearings.

RAY: In cases like those, the manufacturer would have every justification for denying warranty coverage on those affected parts.

TOM: Sure, you can always argue with the dealer, but you'll probably have to take it to court to get satisfaction. And believe me, neither Mr. Magnusson nor Mr. Moss is going to show up in small claims court to help you plead your case. And the dealer may very well win.

RAY: So we think avoiding "high-performance" parts on a new car is generally good advice, Cathy. And we're sticking with it.