How much ws-23 and polar blast to add to existing juice?

It's like the cold that you get from mint bit without the mint taste.

Why not start with 0.5% WS-23. See how much that changes your mix. Then you can add 0.25% of the Polar Blast and see what effect that has. Then if you want it cooler you can add another 0.5% WS-23. 0.5% WS-23 is usually enough for most people who are new to cooling. You do build up resistance over time