RE: big stik 40 underpowered?
Hi,
You could try several different options: larger tires, smaller pitch prop. I would go with the larger tire first. Maybe a 3" - 3.5" tire would work. I fly with a TT 46 PRO, and use a 3" wheel. I also use an 11/4 prop vs a 10/6 or a 10/7.
Just trial and error.
Happy Flying!