I've got the Power FRK and the cam sprockets (Lennie's Sprockets) on my 07 1200GSA and it kicks ass! It does what it says it does. I have not put the bike on a dyno and I'm not going to. I don't know if it increases HP and don't really care. I do know it has changed the bike and that it performs a whole lot better than it did OEM. The flat spot is totally gone and the engine is livelier about a 1K RPM sooner than OEM. It makes the bike more fun to ride and the power band is now in the perfect spot for the type of riding that I do (City commuting and open highway touring).
I am completely satisfied with the product, I'm glad this was available for my bike, and I won't be taking it off.