As much as I respect Mick's work, my ears strongly disagree with him on the V-Cap upgrade. The difference was immediately apparent the instant I fired my Chardonnay back up. And I don't mean by a small margin. I think there are others here who installed the V-Caps after I posted my results and I think they had the same impression I did. I went from the Auricap to Mundorfs which was a nice improvement, but the improvement from the Mundorf to the V-Cap was substantial. There is no doubt in my mind that the leap from the Auricap to the V-Cap would be huge, unless the Auricaps have been changed since I used them. V-Caps are now used in many of the highest-end crossovers, amps, preamps, etc. and the reports from listeners and manufacturers alike are all the same. The V-Caps are stunningly better.
To be honest, I think Mick simply tries to discourage owners from modding his preamps because I am sure they can be easily screwed up. I have read anecdotal reports of modded Suprateks for sale that apparently sounded like crap. Ultimately, the blame falls on the Supratek name and not on the person or modder who screwed things up. So if I were Mick I would also recommend leaving the preamp in it's stock form.
As far as which caps and what values to change, the coupling caps are the ones to change. Sorry I can't give you the values in your particular preamp because Mick may have changed the values in the Chardonnay since I purchased mine several years ago. It should be easy enough to look on the Auricaps and discern the values.