Check out what Peter Ayache has done with his UF. He put a BF100 in his which is more comact than a P120 but puts out similar thrust @ 27 lbs. I also think he sells the engine for about 2500 so a pretty good value. I have seen/flown Dean W's fly with a P100 JetCat and it has really good performance. The UF is a lot slipperier than the Classic.

I flew my Classic Flash with a Merlin 160 and it was ballistic but was a real handfull and was really tough to land until I put crow set-up in with the flaps. (Too much residual thrust)

Carf sells a sadlle tank kit in place of the wing tank that adds lots of capacity:

http://carf-models.com/public_carf/p...ory&proId=2772

Cheers,

PaulD