Unlock Pura by doing 50 consecitive boosts in a track in Adventure mode with the Bandicoot team.
Unlock Fake Crash by doing the same thing, but using the Cortex team.

Here's an easy way to do it:

If you go onto any ordinary track you won't be able to do consecitive boosts. You need to choose the track HYPER SPACEWAY.

In Hyper Spaceway there is a blue, transparent pipe in the last part of each lap.

1) Do 2 boost turnings by pressing R1 once and then quickly pressing right. Then press L1 twice as the speed dial changes from green to red.
2) Then quickly jump. That will make 3 boosts.
3) Repeat steps 3 and 4 until you make 50 boosts.