It seems that, like the Me-109 before it, the model gained about an ounce between prototype and production. That is a HUGE difference in performance potential. Unfortunately, the later, solid foam wing Me-109s gained yet ANOTHER ounce over the originals. Amazingly, it still could stagger through every stunt in the PAMPA pattern! Not good, but better than the 10 point minimum (11? 12? at least you could recognize it).
I put a (real) Killer bee in a Hyper Viper with a balloon tank, on .008 steel lines, and it was good fun. Not competitive in our area, but quite acceptable as a trainer/practice model. (Our competition models push 500 points flown against "the big guys")
The original Killer Bee had the "Killer Crank" which has a cutout around the crankpin and the pin with a hole drilled down the center. The cylinder had slit exausts, but the lower exhaust slit was wider to allow sub-piston induction. The cylinder also had an extra "flute" in the bypass on each side to induce a swirl to the mixture as it entered the cylinder. Finally, the bore and piston were taper honed for maximum performance. A real Killer Bee would turn an APC 5.5 x 2 prop at 22,000 rpm on 30% nitro. The needle valve had to be lightened up to keep it from backing out at peak rpm, thus the yellow plastic extrusion extension. Later, Cox just renamed the basic, garden variety product engine "Killer Bee" and roped in a lot of suckkers.
Buyers beware!