I have only been riding my SXR for about 3 weeks now, and I have been able to sub it (not consistently, mind you), turn sub it, and
almost pull off a nose stab. I haven't tried the fountain yet, I hear I need a bilge before trying that stunt- a lot of water comes in.
Like someone else said on here- SPEED IS YOUR FRIEND when it comes to the sub. I got really frustrated when I was learning, since all I was doing on my last jump was landing and skimming- barely getting the nose buried under water...and couldn't pull off the sub. But if you have enough speed, I found it is a piece of cake. I use this rule of thumb: if you feel you are going too fast to pull off a sub, then you probably are going the right speed.
Hop, pull the feet up in back, push down on the bars and look at the water and nose of the ski, and once you feel it go under, hit the throttle. You should be able to pull it off.
Oh...check out this:
http://www.sixsixone.com/Catalog_66...&product=2478e68f-1dd3-41c8-8812-a47ca3f5679a
for helmets...