I dunno if it's already been discussed in this thread but I have noticed there are
some kind of priorities in the game on which badge it gives after the race.

Does anyone have any idea on how many boost starts does it require to get the
Boost Start badge?

And also, is there batter boost start than the floor-it-when-it says-go? Because
it isn't that hard so I would imagine everyone gets a boost start in the beginning
unless they're picking their nose during the countdown.

I got 31 of the badges. The ones I don't have are the mentioned Boost Starter
and the Low Roll Winner.