As you won't agree on removing every single top time of all the players who get banned for cheats like speedbost, lamppost mod, ab, etc. Why don't you just look for a just banned (or just found cheating a time on a race) player's name on
players board and on "Highscores" section you find presumed
cheated tops. Easy and fast way to find thousands of haxed tops.
Note it's not necessary to remove lower than top1 times as they can be surpassed (that's just to pay attention on top1 which are like 5-6 per cheater).