IIRC It's 30A Main, 20A Signals, 10A Head and 10A Tail...
If you fit another fuse-holder into the main feed from the battery (single thick red wire with single HD connector in it) you can slot a 30A fuse into that and then reduce the Main to 20A). I think that's what is OEM fit on the Specials...
HTH
Miti