The possibilities are endless. Low end is easy to accomplish.
Prop - 9/15 will be a good choice
Stubby pump cone.
I would get a bpipe ( not sure if it’s in the budget)
Then I would do some hull/steering mods
Quick steering mod
But like jarret said, riding and...
I’ve seen tem pull a superfreak out of his van in 3 pieces and literally just hand it to somebody...”here take this”. Probably weighed 35-40lbs in that form, if that. I know don usually builds his in kit form because he has it down to a science now. He has particular things he wants or adds...
I’d immediately go to the one way valve. I had a kart tank doing the same thing (not on 3 trick combos, I can’t even do one) Any time the ski was upside down it bogged 4-5 seconds and cleared up.
Second would be blowing out lines and replacing filters
Also check carb filters in the inlet...