I had the exact setup and here is my results: With a YS 120 the bibe was a blast to fly but would not sustain a hover forever with a 16-8 APC prop.It would eventually fall out.I put in a Saito 180 and wow!It still flys great and will accelerate out of a hover.Downside,I had to put in a 24 oz. tank to give me a safety margin.The Ys 120 loves fuel and the Saito is an addict.My advice:If you do not already have a bigger motor enjoy what you have( i already had the 180)I could not tell any difference with the added weight.The 17-6 might give some added thrust but I did not try it.The Bipe is great fun. Dave