Edit: I thought I was posting in the Accessories and Mods section. I'm going to derby over there, can a Mod please delete this thread? sorry.
I went with a kit from Sprocket Center consisting of a 15T drilled countersprocket, a billet quick-change carrier with a 43T alloy rear(+2 teeth from stock), and a DID ERV3 chain. The quick-change carrier comes with tabs that keep the cush drives from backing out which they tend to do sometimes, so that's a plus. Also fitted a case saver insert in case the chain breaks for whatever reason. I have noticed a slight improvement in smoothness at lower speeds, nothing really significant. Everyone raves about the difference a 14T sprocket makes, so you might see a bigger difference there, but it's ever so slightly harder on the chain so I went up two in the rear instead.