(If dutch members mention "tuned" actually they a mean ported cylinder)
If you have a horizontal minarelli or piaggio engine the stock reedcage is excellent. The Stage6 Pro comes with carbon petals, use those and you're all set. With the rest of your setup you'll be looking at 12hp.
The stock crank doesn't live forever, but if it's still under 7000km it should last for a while. In the long run it's better to replace it.