Mike while I think the Enya option is very good... Tower's RC .15 OS LA for $89 and cost of Lee Machine venturi and NVA might be the better option in a NEW engine
Literally no break in needed for the OS LA vs Enya ( I like the Enya) .... OS LA is slightly lighter
Before you decide, check out and search .15s on RC groups and RC universe....I have seen this size in ridiculous low prices
The Enya .15 CSX is an ABC motor so requires no more break-in than an OS. Also, the OS is rated at .4HP while the Enya at .52HP. By the time you buy an OS Max (if new), replace the remote needle valve with a venturi and NVA, replace the junk plastic backplate, you'll end up with as much money in it, if not more, than the Enya. And less power to boot.
Don't get me wrong, the OS is a good motor but ounce for ounce, I get much better performance and longevity from my Enyas. That said, a good OS FP or LA will pull any small plane around with authority.
I like RC Groups. I've bought probably 15 engines off there.