From my limited experience with FACs, ( only installed 4 sets so far)I have learned that the correct springs will have the best outcome .
A small example: Wirth springs with FAC s on my tribute bike work very well (as a good 1970's front suspension anyway ).
Wirth springs with FACs on my Cali 1100= not so much . Very little travel, (too soft) and bottoming out excessively . No heavy fairing used and 180 # rider
Only way I got any improvement was to use bespoke non progressive springs. ( Sonic Springs).
That took a couple tries, but now the FAC dampers are now doing their job, bike is well suspended for my weight . YMMV