Can anyone explain the modification done by Fortin to 2203’s to add the girth and grind pots

[volcomstone]

Hello! I’m a new member to the forum and was wondering if anyone had any info on any of the Fortin mods not including the Cali mod. The two controls in the title are the ones I’m most curious about but really absolutely any information regarding any Fortin amps would be greatly appreciated.

I’ve searched all over the place with no luck, but as I’m new to the community it could be I’m just not looking in the right places

Jesse