My brother looked into having a stage 4 kit installed when he bought his 2017 CVO SG and the dealership told him labor would be $1400. He ended up doing the stage 1 (exhaust and tuner) himself. A short while later, we did the stage 2 to his bike ourselves, which consisted of adding a cam to the stage 1 setup. A stage 3 consists of adding a piston kit to the stage 2 setup and a stage 4 consists of adding CNC ported heads to the stage 3 setup. Having said that, you wouldn't have to buy any of the parts over again (well, maybe a bigger cam) as you advance in stages, but it would be more cost effective to go straight from a stage 2 to a stage 4 because the heads will have to come off anyway to install the stage 3 kit, so you might as well have the heads worked at the same time. To take it a step further, you could not only have your machine shop CNC port your heads, but mill them for an extra bump in compression and add bigger intake and exhaust valves and heavy duty valve springs.
