Those Lipo batterys?
I calculated your wing loading and it's 27.0 oz per sq in.. Real good.
The new muffler is about 3.0 oz lighter and if not using Lipo's you can save another 5/6oz or so for a total of 8/9oz which is a half pound. That would change the wing loading to 25.9 oz per sq in which is where most all the top of the line 50cc class Yaks are when they weigh 16/17lbs. They come in at 25/26 oz per sq in.
Plane looking great, thanks for the imput and pic's.
Got a video coming?????