This is a quote from the EDGE Products FAQ for the Edge Comp. I think it does a pretty good job explaining what is involved with warranty and electronics enhancements.
"While the answer is straightforward from a legal standpoint, we also want to educate our customers (and after-market consumers) on some industry realities and offer some common sense precautions to minimize your risk. Consumers of aftermarket products are protected by The Federal Magnusson-Moss Warranty Act. The Act states that if something breaks on your car and you take it in for warranty repair, the dealer must honor your warranty unless they can prove that whatever modifications you have added to your car actually caused the problem.
While as a consumer you have strong legal protection regarding your vehicle’s warranty, there is also a practical reality that different automotive manufacturers and dealers have greatly varying views on aftermarket products, in particular those that produce horsepower, such as performance enhancement chips, modified intake manifolds, or aftermarket exhaust systems. There are dealers and manufacturers out there that will use the presence of a horsepower upgrade to void your vehicle’s warranty. They will do this regardless of whose product you are using. Any aftermarket company that does not acknowledge this is misleading you.
The bottom line is that while the law protects the consumer and provides for enforcement of the warranty, it is very difficult for most people to hire an attorney and fight a voided warranty. Edge recommends that you always disconnect and/or remove any performance device or programmer before you take your vehicle to a dealer for any service, in order not to interfere with
Diagnostic equipment. "