I dont know about the .18 but I do own a M16 (it's the same thing as the Q16 but it's an older version, they have now renamed a marine engine the M16) and it's not a bad engine. Kinda hard to tune at first but once it's tuned it's alright, it's reliable, holds it's tune, and isnt a bad engine overall. But there power is drastically over exagerated, the engine I have said it makes 1hp but it's more like .5hp. So if they say it's 1.8hp expect it to have like .6 to .7 hp.

If I where you I would look at the O.S .18CV-RX. Now I cant seem to find the price or the engine on megatech's website so I cant say hopw much it will cost. But the .18cvrx is probably pretty close in price and will be way more relaible, more powerfull and easier to tune, and it's from a name brand engine manufacturer.

Or maybe even the .18TM as it's a direct drop in for the 2.5 and the 3.3 and can use the ez-start. Very powerfull engine, thats also reliable that or the cvrx is the way to go.