I asked if PSAudio would install the upgraded transformers and received this reply from Scott Schroeder. A kit would be another thing altogether of course…but it would be a different model I suspect like the upgrade from PWD to DS.
'Unfortunately, we are not able to install aftermarket parts in our products. This is for a few reasons, the main being that we strive to maintain a consistent and expected level of performance for all of our products - modifications kind of throw that out of whack. Of course we support folks making their own modifications and improvements - it’s just not something we’re able to get involved in.
Additionally, all of our tests are designed with certain parameters in mind, and some modifications (for instance NOS tubes in BHK amps and pres) cause the products to fail our Full System Tests. And for better or worse there is no way something that has failed FST is ever going out the door - our production guys would have a collective aneurysm.’