A "service writer" does not work for Ford. Ford provides your warranty, not the dealer. Too many service writers are on power trips and sometimes need Ford to clean their clock for them. Many spend so much time BS'ing people they start to actually think they know something about cars. If you have tunes other than the MP-215 and have engine problems you can legally be denied coverage on your engine if the failure is related. If you have a dealer that is refusing to work on your car and the problem has nothing to do with the mods Ford will cover it. Take it elsewhere, your dealer is an independent contractor for Ford service. Your dealer is NOT the Ford warranty authority, Ford is. There is a-hole dealers and good ones. If you buy from a mom and pop dealer that sells mostly f-150's and SUV's you can expect grief from them. If you buy from a Performance dealer with lot's of ST's, Mustang GT's and Shelby/Roush cars and a parts department that stocks and a service department that installs Ford Performance parts you will have zero problems. STOP blaming Ford for bad service writers that get their jollies from jerking people around to help their weak ego. Do not settle for a "service writers" BS. Ford customer care folks have fun telling them what they will and will not do. They have zero "authority" over your warranty. The dealer IS NOT obligated to work on your car if they do not want too! But Ford can "convince" then to do it! It becomes a question of do you really want people working on your car that do not want to do it? Most "service writers" have seen very, very few ST's, one dealer I stopped to car shop for a Fusion Sport had salesmen coming out to see my car because the had never seen one. In 2017! Not a dealer to take my car in for service at. On the other hand where I bought mine is a Roush dealer, had several Shelby's in stock and had 9 Fiesta ST's when I bought mine. They gave me a price which included the Mountune MP-215 installed along with the RMM but ended up doing them on my own and registering them with Ford. If I have problems I feel sure I will get zero grief for those or other normal mods like exhaust, OCC or FMIC at that dealer. Because my MP-215 is listed on my warranty I will have no problem once the dealer makes the call to Ford if they question it. Most dealers know zero about the Mountune stuff. So if you have an asshole dealer/service writer call Ford and raise hell or take it to a dealer that sells and embraces mods. But keep this in mind...most of the "techs" doing warranty work are part time and beginners. New car dealers are where beginner mechanics get "experience". My son got his at Ford, Nissan, Subaru and GM and seldom saw 40 hours a week. His true stories are down right scary. One that terrifies me is the sweepings from the service area and how many nuts, bolts, screws, lug nuts and plastic clip parts that did not get put back on cars. My experience on warranty work has been a missing oil drain plug and zero oil in the car, my new Buick Turbo was 4 weeks old when it sat D.O.A. at the dealer for over 2 months waiting for a new wiring harness. But they did offer to RENT me a car! That was the last GM car in this family! My new Capri RS made it 6 blocks from the dealership when I pick it up before the entire clutch pedal assembly fell to the floor. Never had a bolt in it from the factory, I paid out the butt for "Dealer Prep" and they never even drove the car! Or Nissan telling me my rear drums were worn out but front disks were "like new" at 60K. I told them to change both....then the front rotors needed turning (not) and the beginner turned them so thin they grabbed and pulsed. Took it back and they offered to give me my money back and I could take it to a brake place because they "didn't really have anyone with brake experience"! At a large Nissan dealer! My car (2016) has not seen the dealer for any reason yet. But I have to get a new Sync 3 system so no choice. My experience is the majority of "service writers" would need a manual on a screwdriver to operate it and when they learn to operate it they can get a raise and work on the cars! And we will not go into how many times the "Service Writers" attempted to or did rip off my mother, wife and daughters! So called "Upgraded" my mother to Nitrogen in her new tires for only $75.00......a-holes! I put them between a slug and a used car salesman in the evolution chain, just in case there is any doubt about my feeling for them!