I'm buying two pre owned 8.2 Mercruiser mags 380 HP. What is the difference between the standard and the HO? So far looking at part numbers, the only difference that I see is the little adapter that holds the flame arrestor. The ECU has the same part number, so I assume that it would have to be programmed to the HO's fueling, timing curve, if so, who can do this? Thanks!