um, you are in CA. why the hell are you taking off your cats. if you get pulled over and the police even look under your car and dont see cats, you bank account is $10,000 lighter. the dealer can refuse to work on your car if they choose because your car is in violation of numerous laws in CA. the magnussen moss act covers things like oil changes, tires, filters etc. however removing your cats is illegal in CA. when you see them listed in catalogs notice they dont have that nice and pretty "50 state legal" or CARB approved picture next to them. if they dealer really wanted to be asses, they will call the police, and when you leave have a cop waiting to pull you over. the ford dealerships usually have contracts with police departments to do major services to the interceptors. so its a you scratch my back, i scratch yours kinda thing. and if you do decide to go ahead with taking your stock pipe off, keep it, THERE ARE NO LEGAL MIDPIPES IN CA EXCEPT FPR THE STOCK ONE!!!! the only aftermarket cats you can use on 96+ cars is the magnaflow cat, and the car must be out of the state required 8 year/80,000 mile emissions warrenty. the magnussen moss act does not allow you to put on aftermarket cats in CA, because the only legal ones to run are stock.