1.) In regards to pneumatics brakes + fins on the axle:
a.) Don't use air brakes. If were me, keep the brakes simple (drop brake or something), strap a paintball CO2 can to the driver's leg, and hook it up to the blower using a quick-release mechanism. I can think of a ton of creative ways to hide all this, plus the GPS pcb/battery.
b.) Pneumatics give the appropriate amount of boost to not raise eyebrows. Which brings me to....
2.) Electric engines. Looking at low-end torque values, and battery energy-density/weight ratios, electric engines are:
a.) not easy to conceal. First of all, electric motors get a fuckload of low-end torque, so, depending on how it's installed (a good engineer could get around this with gearing), you'd see the difference in speed as soon as it clicks on. Also, the motor and batteries are bulky.
b.) If we're talking about weight, which I will get to, batteries are ridiculously low energy density for their weight. The fact that batteries have basically not progressed in concept since their invention is an embarassment to chemists (of which I am included). Gasoline stores orders of magnitude more energy per weight. You might as well carry .5 oz of gas and a tiny combustion engine, probably comparable in weight.
c.) Makes you wonder why there ARE 8 extension cords plugged in for one truck.....(Joke, I'm sure they don't use electric motors). In all seriousness kids, if I were in charge of the rules, a ton of electric heaters are just as dangerous as a solvent left open in the truck. Combine them, and ... well, just be careful not to repeat the 80's.
We mechanics are obsessed with shaving off those last few pounds. Unfortunately, as well as we do our jobs...
a.) one pound might be well within the swing of a driver's normal diurnal weight swing. Heck, if she hasn't gone to the bathroom in over 12 hours, that will do it...
b.) As light as the buggy is, a bad performance by a pusher will eat up quite a bit of time on the course. Whether a lighter buggy makes up for it with the other pushers and the freeroll is up for debate, but a bad hill 2 can easily kill those 17.66 repeating ounces you took out of the steering.
c.) I think rolling resistance and energy loss to the course might be worse than any weight gain.
So, a 2-pound pneumatic might easily pay for itself if it gets + 2 seconds free roll and a great hill 3 roll out. I'm not advocating it, especially because the engineering that would go into it would be better spent improving steering and weight, and the time spent on it would be better spent sanding (!@#*&).