I have switched from the saito .72 to .82, no mods required, direct bolt in. definately worth the expense. with pro zinger 14x6 with hover at less than half throttle with true unlimited verticle and now has the power to knife edge loop. balances with no added weight at 5lbs 5oz. i am finally content with the performance. tried apc 14/6, but the engine can swing the much lighter pro zinger with more authority and apc required adding tailweight to get the cg.