RE: CG Ultimate or GP Super Skybolt?
I've had 3 Ultimates with YS 1.20s and 1 with the YS 1.40. The 1.20 versions were Unlimited and the 1.40 version was very unlimited. With the stock servo set-up (except 2 in the wing), you'll need about an ounce of tail weight with the 1.40. I've never flown one with the 1.10 but I've seen the .91 air chamber fly and it was under-powered in my opinion. If you can find an older YS 1.20, that's probably the way to go but the 1.40 is definitely not going to rip the plane apart.
A few modifications:
1) cowl, pants and gear aftermarket
2) reinforce the gear mount with triangle stock
3) as someone else said, 1/16 ply on the cabane mount (make sure you put it on the bottom side to avoid jacking up the cabanes)
4) chop off the 1/64th ply at the read turtledeck former and carve balsa blocks (otherwise, you get this goofy looking flat look of the turtledeck right above the horizontal stab.
5) box-in the ailerons about an inch inward (looks nicer)
6) use 6 inch wide balsa on the tail surfaces to avoid an unsightly seem
7) taper the rudder and elevator to a nice air-foil shape
8) taper the rear of the interplane struts to a nice airfoil shape
9) use Robart hinge points (countersink them for flush)
10) extend center wing sheeting 1 wing bay
11) don't glass the center-section (it's a one piece wing). I've points the airplane straight down at full throttle and jammed the sticks in the corner until the plane blurred into an inverted flat spin and nothing has every broken (at least 50 times)
12) ditch the stock motor mounts for something made of metal.
Have fun...this is making me want to build another one.
Mike