I had my engine swapped with less than 1,000 miles by ford under warranty and I had the mechanic put my mac lt's on the new engine while he was doing it, they charged me 6 hrs for the install, ( when I had my exhaust changed afterwards we could see where the ford mechanic had try to put the engine in the car with the lt's on and it dinged up the undercarriage a little bit.) I remember them saying they had to do a little grinding, although I didn't notice anything while it was on the lift later.