I was going to get my ECU remapped. Some tuners ask for the ECU to be sent away and it comes back reprogrammed. I am reluctant to do this with my original ECU but I considered buying a 2nd hand one and sending this away instead. Is it simply a case of plug in and away you go or are there all sorts of other issues that would prevent this from working? (I know that taking my car to specialist tuner with a a rolling road would be preferable) Thanks.