I just go the jib kit for my Wave about a month ago. Definitely faster (I can't say how much, but quite noticable
in the 7-15 knot winds I usually sail in. I would agree that a better system to tension would be good (I plan on trying Rick's
method using two pieces of stay-cable across the bows and avoid connecting directly to the spreader bar.
I might also mention that the jib saved my buns the other day. I got caught out in gusting-to-28mph weather and dropped the main
and sailed home using the jib only. That was pretty quick downwind sailing even with the tiny jib let me tell you!

barry