I engaged in an email exchange with Rob last week re upgrading the caps on my 3.7s. He told me "To upgrade the CS3.7, a 76uf, 151uf, and a 16uf cap would need to be installed in each cabinet." I was unable to find these values. He then suggested "The values I listed are the values for upgrading the CS3.7. It is possible that the capacitors may have to be purchased with the values described (NB: in the catalogs). For example: The 76uf CSA cap may have to be summed from a 75uf CSA and a 1uf CSA cap. The 151uf cap may have to be summed from two 75uf and a 1uf. The 16uf CSA cap may also have to be summed from a 15uf CSA and a 1uf CSA."
There you have it. I'd like to do this, but do not have the technical acumen. If Thiel Service offered this, I'd jump. Also, there a lots of varieties of caps out there, and it's a little scary for me that I might alter the speakers in a way I did not like!