Upon my research I haven't reached a clear answer. I am looking into getting an ECU for my build, problem is that it's from a donor car that is a different model but same ECU. Will I be able to do a full write to reflect my engines tabs and tune. Or will I have to go to the dealership for a flash? I'm sure this has been answered many times, but I don't feel comfortable and clear with my search.

Thanks in advance