Originally Posted by Urbanracer

It pretty much depends on the dealer, some are better to deal with then others. Most dealers will still honor the warrenty on the car as long as the parts you've added haven't directly affected or caused problems with the car. If you get a CEL, chances are they won't fix it under warrenty with HFC's on your car. If your window regulator stops working, they don;t really have a reason not to fix it since your HFC's would never affect the performance of window regulator.