150cc is the 'hard' difficulty of the game, in Grand Prix the 150cc mode contains only karts and expert level rivals. Its also much faster, so says the name "150cc", which basically means faster, more power karts. The only thing more difficult then 150cc is Mirror Mode, in which it is the same 150cc, but, with reverse right/left (Ex: Right turn would be left, left turn would be right, very confusing). That is the most confusing mode, as you've been used to driving the track one way, but now must learn another way.
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