The law from SEMA on warranties and aftermarket parts:
http://www.sema.org/main/semaorghome.aspx?ID=50096
Quote »The Law
Federal law sets forth requirements for warranties and contains a number of provisions to prevent vehicle manufacturers, dealers and others from unjustly denying warranty coverage. With regard to aftermarket parts, the spirit of the law is that warranty coverage cannot be denied simply because such parts are present on the vehicle, or have been used (see Attachment A).The warranty coverage can be denied only if the aftermarket part caused the malfunction or damage for which warranty coverage is sought. Disputes in this area usually boil down to arguments over facts and technical opinions, rather than arguments over interpretations of the law.[/quote]I'd double check the conditions of the warranty, but I'm pretty certain by the information stated from SEMA that you are covered unless that part causes a malfunction to another part you're trying to get serviced under warranty. (Ex. Your intake takes in water and damages your engine. Your intake is at fault and NOW your engine is no longer under warranty)
Don't let them try to scare or bully you. It's the law.