The Rubig is not faster than the Aixro, at least not from the videos I have seen. Search youtube and the are a few videos of the Rubig running against shifters and the Aixro. It appears that the Rubig is a monster when it comes to low end power and has alot of pull out of the corners, but is not as fast on top end. The videos I have seen show the Rubig opening up the slightest of gap out of a low speed corner, but all the karts either closed the gap and were on it’s bumper or pulled even with it or passed it in the straights. Never seen one in person.
Richard said he has a Aixro with only 4 hours on it for sale for $5,000. That included carb, pipe, PVL ignition, ceramic bearings/seals, engine mounts nad new Freeline radiator. Pretty much a bolt on and go package.