I know these balls are old but I seem to be lacking balls in the middle of my range. I wondered what exactly is the difference between these 2 balls. From what I gather both have exactly the same RG and differential and both are PK 18.

I know the Time Zone is asymmetric and thus the reaction can be fine tuned using the PSA but I really dont see any other difference except how the cover is left at the factory. Can anyone enlighten me further? Has anyone drilled both 'the same' (i accept this is not entirely possible with the PSA). I am thinking of getting on, but am more inclined to get the Nemesis and save a few quid.