The original SEX 2.0 (first stereo SEX, 2004) used the PC-1, a plate choke of about 25 henries.
When we introduced the current version 2.1 model, we significantly upgrades the plate choke and output transformer - that's what you have. The PC-3 has about 40 henries.
The available Magnequest upgrade package includes the BH-2 plate choke, which has about 50 henries.
The Magnequest is a big upgrade from the original PC-1, but only a modest upgrade from the current PC-3. I believe it's only sold with the matching output transformer. I have the MQ package (with nickel core transformer) in my personal SEX amp. IIRC, Doc B had the same but sold his in favor of the current production. The sonics are slightly different, so it's a matter of taste and preference.