I've registered on this website just to say thank you for your MOC and instructions. I bought the kart on my holiday and had much fun building it, but the B-Model was a big letdown. Yours is much better as it keeps all functions and looks great!
I've changed the model only slightly for aesthetic reasons. The main thing I wanted to change was the height of the rear spoiler as I feel it looks better when it's a little lower (although I had to cheat a bit there and now the back compartment won't fully open). I also slightly changed the steering to make it look more like a F1 steering wheel and to loose the protruding pin there. I also added the hose to the engine and slightly changed the seat. I have no idea if this interests you or anyone else, but I've added some small pictures of the changes.