Verniers are not something I would be interested in. Primarily because losing the VVT hurts spool up really badly, and then the fact it's a complete mission to adjust them. I'd probably go for HKS step 2, Tomei apparently are coming out of China now and there are reports of the cams snapping.
That, and a decent wastegate would see more power. Honestly though I've spent more than enough on this car this year and hardly gotten to drive it at all so I'll just enjoy it as it is for a while. The stock long block is pretty much at the upper limits of what's usable too. Any more and it'd be best putting in some pistons and head gasket and studs.