Depends on how you intend to fly it. If built to their web site stated weight of 16lbs and you just want to fly it around, then something smaller in the 12lb thrust range would be OK. On the other hand, if you want to do some of the high-alpha and other cool maneuvers this jet is capable of, I would go with something in the 16lb+ range.

I have almost 1 to 1 thrust on my BV Rafale and really like the way it performs, including the high-alpha stuff.

Craig