Looking at this video it appears (at 0:06 et. al.) as though he has removed the sponsons from the Spark . That'll let the rear end slide around a whole lot more than with the sponsons on. I tried doing some of these tight turns today on my Spark and on my old GSX and the Spark has a ton more grip. The old GSX will slide all over the place - the sponsons are higher and more rounded than on the Spark.
He also has IBR (which means he has the HO spark) and might have VTS as well. The VTS will let you trim the bow up and make the ski spin around much easier.
Now to take the sponsons off and see how it changes...>
The supercharged Sea Doo looks great but the Spark looks more fun.
And yeah it seems like the supercharged Sea Doo's hits it's red line super quickly - almost like it's cavitating and needs a wear ring.