Gentlemen, Here's my experience with the HE Leopard. I gutted the whole thing and used HL electronics. Pershing tracks were used to replace the "rubber bands". HL Pershing gears and sprockets were installed. To accomidate the new tracks, I machined pvc spacer rings to reduce the gap between the wheels. During test runs, the tracks would still slip off. I discovered that the torsion arms flex and twist quite a bit during turns and pivots. thus letting the track slip off the sprocket. One will definately have to replace or manufacture stiffer torsion bars.
I then gutted the turret and installed a co2 cannon ,thanks to the "My ultimate HL airsoft upgrade" thread. It works great, but I have to figure out a bb feeder system. Here's the thread on my Leopard [link]http://www.rcuniverse.com/forum/fb.asp?m=6707827&key=leopard+2a5[/link]