B&W CM10 Mystery Cap?

I own a great pair of B&W CM10s, low to high seems to be how B&W prioritized parts quality across LF to HF crossovers. LF begins with an average electrolytic, then into the HF which also covers off the mids - they step it up to a mystery film cap, on to beautiful Mundorf SilverGold Oils for the tweeter.

I suppose on some level this is the way to do it, if one were a manufacturer, but leaves me thinking there is improvement to be made and mids are my target. I was thinking of placing a 0.1uF bypass cap on the yellow mystery cap as a safe bet for a boost and thinking Mundorf Supreme SilverGold.

Here is a pic of the mystery cap in question - what do you think of this plan? Good? Or scrap it and just replace the cap with something expensive and be done with it ?