I think your definitely on the right track with either the 100 / 120 / 140 size turbines, I wouldnt be tempted to fit anything larger than this, we have a Merlin 140 in our UF and it feels so well balanced compared to my 160 powered Classic Flash, I had a Wren SS in mine originally and while it was nice to fly it always felt like it was cruising round with no option to go any quicker, now Ive fitted the 160, while its absolutely balistic and fun when its flat out, its hard to find a point on the Throttle position where its not at least 50 - 60mph faster than it used to be, I know some guys will say they are sure Idle would cure this but flying an aerobatic routine with the throttle set at partial settings I find a little awkward.

I had a flight with two 140 powered UF's last weekend and just thought they seemed alot nicer to fly, maybe its just me, I dont know, they just felt alot smoother and easier to fly due to the slightly lower top speed and what seemed like a more linear throttle curve.

Theres also been a few of the our club members that have dealt with Gaspar and couldnt speak highly enough of him.