But if the car it was VIN locked to is returned back to stock doesnt it mean the unit can be used for another car? I thought that if they dont return it back to stock then you have to send it to CAPA and provide proof of purchase for them to reset it?
Replacing the cat will require a retune, which ford can detect on their scanners and void your warranty if anything blows up. K&N Panel filter and typhoon secondary intake is pretty much it.