Uprev question - Not asked before

seymore4

It doesn't "do" anything. Its just a newer version of the firmware that updates that specific ECU. If you look on the Uprev rom support matrix you will see a bunch of different ECU #'s listed, with an "uprev master rom" next to them. The master rom is the most recent, up to date version that overwrites all the other roms listed next to it. As Uprev's engineers come across the various ECU versions they check them all for compatibility and assign the master rom, which we use to tune with. There is no reason to update to the new rom if you've already been tuned, but on a fresh tune you would want to use the "update" listed.