I have this kit and it has been sitting in my basement untouched for 2 yrs. There are 4 or 5 at our field and they are powered by a side mounted OS 71 Surpass's or a side mounted OS 46FX's & now a 50SX with a Pitts muffler with 2 outlet tubes. I was going to side mount my ENYA 50CX and get a Pitts muffler but LHS said there isn't such a muffler for that engine. Looked into doing what I think you are intending to do but you have to cut away to much of the cowl and go into the engine mounting wall. So my GP Ultimate bipe sits there. It was Christmas gift and I hate to tell my wife I'm going to sell it un-built. By the way, I ended up mounting my ENYA 50CX in a NEA BelAir 40 bipe. terrible kit, and pretty good engine but I just sold kit/plane a month ago. New owner loves the combo but I simply need to sell if I want to build more planes this winter.