I've listed two more modification services to the site, based on some things I've come up that I think add real value to the products mentioned. I've been asked by a number of people if I will upgrade this or that microphone that they have, or if I will eventually mod the entire WA product line; and the answer is probably not. I will eventually offer more mods; but each of these takes quite a bit of time to research on the bench and voice and test out and send out for testing, etc; so I'm giving that a break for a while to focus on my own mics. As for the WA product line, no, that begins and ends, I think, with the '47' mods. I'll explain why.
I certainly think just about anything can be made to sound better when it was designed with initial cost and engineering restraints in place; but there is a law of diminishing returns where it becomes too prohibitively expensive for the supposed benefit. The ones I do offer are pretty clear-cut examples of where I can do a lot of good for reasonable cost and with little waste. That's kind of my criterion. the other WA products have certain barriers in place, for instance, that make this not practical. I'll go over a few.
The 87 and 251 both, for instance, would require basically an entirely new set of boards to do what I'd want to do with them. To do the high-z section of the 251 floated and point to point (along with new tube, re-voicing, etc), and to give the 87 a PCB kit that was actually reflective of a real U87's schematic (with the proper transistor, drain current trimmer, many polystyrenes, etc, etc) instead of the mystery vanilla sounding China-87 circuit that inhabits it. This becomes too time and cost prohibitive, and also produces too much waste. I'm not drawn to those things. For the 14, for instance, the thing I dislike the most is that it lacks the beloved hypercardioid function which again, would take a new board and some cutting on the mic body to add, and I also tend to think it would benefit from a legitimate AKG CK12 capsule replica. This sort of thing would cost multiples of the mic's retail; and so for that person, it simply makes sense to buy a real 414. And the 84 doesn't need any mods at all.