Hi Trin,
Sorry I can't help you on the sprint kayak plans, although I'm also interested in seeing if it's possible to build one. Just looks like a bunch of fun.
I built a Pygmy Boats Osprey HP (S&G kit) last winter and am building another for my wife right now. I LOVE the boat. It's a real fast, straight-tracking and lightweight sea kayak (comparable to my buddy's kevlar Seda Glider) and, for a rookie, I've done okay in some sea kayak races this year. I also found that I love the feeling of slicing through the water and powering ahead, so I'd be interested in finding the easiest, cheapest way to try out sprint kayaking. Seems there's very few resources for that sort of thing here in New Hampshire and New England. So any additional info. on introductory clinics, etc. would be appreciated.
Good luck and thanks,
Grambo