When I got my LT-40 I had the recomended .40 in it. After a bit I replaced it a Fox .50. The Fox was just a tad heavier than the .40 and made a big difference in the LT-40's performance. I use throttle control all the time while flying, reducing the power to about 3/4 once leveling off after take off, and often back it off to slow it down and just "drag" it around in slow speed. The extra power is very nice for quick, steep climbs, and I always chop power on the downside of a loop and bring it back on when level. There are 4 Lt-40s at our field and the other three have .40s aboard. I've flown the three .40 powered, and I find them a bit sluggish, but of course with the extra "go" of my .50 I have the edge there. If you do use the .60, practice throttle management, or there will be times your plane will be overstressed, possibly with some bad results. If that .60 will run nicely just above idle, it could slow fly that bird all weekend long. Of course there are those who fly full throttle always. Have fun.