Originally Posted by 1slow370

I have flashed different roms on on different ecus using uprev. Find a friend with a cable, have him flash his car back to stock, use it to flash your new ecu with the proper uprev rom for your car, then flash your car with the back to stock rom (again correct for your car) and give the cable back to your buddy so he can re flash his tune on again. My old car has a 08 g37 auto ecu with an 09 370 6mt revmatch rom on it. You will still have to have the dealer initialize the nats and reset the vin on the ecu.