as far as i know a 20 lb. engine would be too much weight and too much stress on the av8r, it is designed for 12 lb. class engines, pcm has a new model for that coming soon the dv8r. bobcat xl will work good with 20 lb. engine, lots of time to build and lots of money though. hotspots are becoming few and far between as far as getting kits go. the kangaroo is the cheapest, all composite, and it comes essentially done, can be ready to fly in a week or less. and a 20 lb. engine will work fine on a kangaroo and probably give you speeds at, near, or above the 200mph mark. allthough you dont want to be going that fast for the first time with a jet.