Drum to disk 11 vs 9 booster

[DC7432]

I'm converting my 67 convert from front drums to disk. GU has 11 and 9 boosters any opinions on which way to go? Thanks

[X33RS]

I do a few conversions here with the 9 inch booster.  If you decide to go that route make sure you get a dual diaphragm 9 inch booster.   I've had complaints from the cheaper single diaphragm 9 inch boosters that just don't apply enough pressure for some people and requires too much pedal effort to be comfortable.  Swapped those for a dual diaphragm and they were much happier.