Or they aren't familiar with the vehicle you are bringing them. Good shops are those that know their limitations and areas of expertise. If that shop doesn't know Fords, are they just supposed to go on your word that those headers are even the correct part number or are a quality brand that is going to fit right? What's that shop supposed to do when they have the car up on the lift and the customer brought them a set of headers he promised would be perfect and they're hitting the steering shaft, the transmission, the firewall, and the X pipe is for a 5.0? Leave it up on the lift, loose money, and spend a week's worth of time fabricating the part to fit right?