karting gave up trying because every time they found a way to police it, someone found another way to beat it. there have been a few serious incidents with fire and people getting sick from the preps so now they basically tell you no prepping in the trailers. there are preps for
everything....harder, softer, less bite, more bite, ect, ect, ect. most times you cant hide the smell and thats usually the tip off.....wintergreen....creosote....thats very very hard to hide but is at the top of the list for preps.
i have heard of guys getting busted for using simple green to wash tires.
and yes.....imo....karters were the first to openly use preps as a tuning device.