FWIW I have had/have several twins and my rules are: (1) Use well broken in engines that are known to be reliable: (2) When tuning them, adjust the slowest engine first, then adjust the faster one DOWN to it. Engines running a bit rich are ok as long as they as they will reliably respond to a missed approach throttle up. test this by making a simulated low throttle approach and then apply "go around power" and make sure the engines both respond without bogging down or flaaming out: (3) Being perfectly in synch is not real important. Engines within 500 rpm of each other will do ok and they tend to synch in flight: (4) When tuning and you think you are ready to go, have a helper operate the throttles while you hold the nose vertical for 30 seconds or so at full power. An engine that might go lean and flame out on the take off may reveal itself. Nothing is worse than a "flame out" duing take off: (5) Let the model gain plenty of speed on the take off run, A flame during lift off at slow speed is almost always fatal to the model, it will snap roll into the dead engine before you know what is going on: (6) Be comfortable using rudder, it is your best friend with a dead or dying engine.: (7) other stuff I have forgotten but you might consider an alternate model from a 38 for your first try. I have had a 38 and they are a bit hot and unforgiving