The Law: What You Need to Know.
There is hope for the consumer, and it's called the Magnuson-Moss Warranty Improvement Act of 1975, codified as Title 15 of the United States Code, Sections 2301 through 2312. It is a federal law, so it applies everywhere in the United States. As with nearly all written laws, there's a lot of legal mumbo jumbo in this statute, but the important provision lies in Section 2302(c):
"No warrantor of a consumer product may condition his written or implied warranty of such product on the consumer's using, in connection with such product, any article or service (other than article or service provided without charge under the terms of the warranty) which is identified by brand, trade, or corporate name . . ."
What this says is that the manufacturer (warrantor) can't refuse to honor its warranty if the consumer uses products made by third parties (i.e., aftermarket companies), unless the manufacturer offers the consumer an equivalent product for free. Since by all accounts Ford doesn't hand out free big-bore throttle bodies, we can safely take this to mean that one may install a Brand-X 90mm throttle body without it voiding one's vehicle warranty.
Though the main intent of Congress here was clearly to promote competition in the marketplace for replacement parts (e.g., to prevent Ford from requiring you to only use Motorcraft oil filters), hop-up goodies also fall under the act's purview. Hard to believe, but it would seem the Feds actually care about hobbyists like ourselves. Although the reasons they give a damn may be rooted purely in antitrust and capitalism, we'll take what we can get.
The Magnuson-Moss Act flies in the proverbial face of Ford and its dealerships that say your warranty has been completely voided because you've installed aftermarket parts. Indeed, this federal law states exactly what we've been stressing: that the warranty has not been voided, and Ford will have to repair the Ford parts in question provided the aftermarket part didn't cause the problem. This legal synopsis is easy enough to say, but it's also easy enough for it to come back and haunt you. Go into a dealership screaming and yelling "Magnuson-Moss" like it's bloody murder, and perhaps even throwing a copy of this article at them, and you've greatly increased your chance that the service department will continue to dishonor your claim, or maybe even go ahead and void your warranty in Ford's system-if they haven't done so already. We'll discuss some more appropriate procedures we recommend for going about such a confrontation-though we wish it would be so easy, simple mention of federal law generally won't do the trick.
The Act also allows companies to set up informal dispute resolution mechanisms that must be pursued before going to court. We mean "informal" in the sense that while structured, these mechanisms aren't bound by rules of evidence, procedure, or legal precedent. Ford has taken full advantage of this in its use of the so-called Dispute Settlement Board (DSB). Administered in cooperation with the Better Business Bureau, this system essentially uses a third-party arbitrator to decide the case between you and Ford. If the decision comes out favorable to you, you can accept the decision, have it enforced, and give up any right to subsequently go to court on the issue. If the arbitrator's decision comes out unfavorable to you, you can reject it and are free to pursue other legal remedies, i.e., taking Ford to Federal Court.
Although Ford can't force you to go through the DSB mechanism before taking action in a state court (for example, a small-claims action or a contract action), the corporation can make you do it before taking it to Federal Court under the Magnuson-Moss Act. This may be a good thing, though, because use of the DSB comes free of charge, and you just may get what you want before having to plunk down the complaint filing fee at the local United States District Court. Though Mustang owners we've spoken to say the DSB system is "stacked against you," anyone would have to agree that an imperfect system is better than having no system whatsoever-unless, of course, you're an anarchist.