Been watching some vids on youtube and noticed that these pkra riders get massive amounts of air then they 'pop'. Question is, is this real 'pop' (45) or do they send the kite slightly when they go into a trick?
Depends, it's a bit of both. Some riders do most of their tricks at 45', but I would say they all put their kites higher than that on a lot of tricks. Guess if you wanna win you need to land stuff.
don't underestimate how fast they're riding either. On the videos, when everything is put into slow-mo and zoomed in, its hard to get context for their speed through the water before they pop.
But Rowdy is right too - when you need to land it in competition, I think they err on the safe side and put the kite a little higher.