I've got one on my stock SX-R and she hooks nicely but is it a $300 gain . . . . ?
Probably not.
I might have to agree with shonuff. For my SJ, i had two pumps one with a 12/17 skat swirl(not c75 prop) and another with a skat 12/17 swirl (not c75 prop) and the TBM pump cone and to me the difference was hard to notice, it might hook up a little bit better in white wash, but like i said it's hard to notice.
Now on the other hand, I was running a stock ported motor w/ daul 44's, pipe, head, msd, and lightened flywheel. so i can't say that i know what the difference would be on a ski with big power.
In my opinion if your on a ski with nothing spectacular for a motor, I'd put the money towards something else like carbs, porting or a head.