If you want to get validated so don't say things like that. I mean it will be all up to himself to decide if he want's to ride a mod or a stock. Since mod bikes hav shorter Wheelbase, it will be easier to take bunnyjumps, but it will be more difficult to take a tapp. If you like tapps, long gaps, and natural... Go for Stock, if you like more urban style, sidehop, bunnyjumps and stuffs like that, Go for a mod.. I'm riding stock because I like natural, and it's much easier to ride on rocks with a Stock bike, and I could do sidehop better when I went from Mod to stock.