I was also looking at throwing this SLP kit in, the kit comes with some venting, an SLP silencer, SLP y-pipe, and SLP head, on SLP's website they do not have the vforce reeds in the kit, so I doubt they are required. From my research, you did get gains, although not near the 17 HP they advertise, but you have to jet up to 410's if I remember right, so your going to be using more fuel, and I don't know about yours, but my fuel consumtion in my 07 is horrible, so I don't know if I want to make it worse.
I think clutching is the way to go like Winter brew says, I am going to put in Dynamo Joe's clutch kit in this fall, and see how that goes, the clutching is much better in mine as well from when I picked it up, but there is still alot of room for improvment, and its still dropping RPM's in really deep stuff.
Venting and clutching, once those are perfected, I might try out the SLP kit
BTW if you do go with another silencer, I would be interested in the HPS if your selling it.