Thing is with a postal map is that the engine condition is not known. Im sure 90% of all people wouldnt know exactly what to look for when taking a car for a remap, such as piping issues, split hoses, sensors, live data etc. It would make a small underlying problem, maybe not even noticable on a stock map, more worse and could kill the engine.
Its those types or remaps id always advise to keep away, IMHO