not really.
what I did to get some extra power out of my cantis was to use compressionless brake cable housing ( like the delta aztec housing), and then also moving the brake pads very close to the rim. when this is the case, the cantis look squashed and spread out, but you get maximum mech advantage, and therefore power.
the only problem with this is that if your wheels are out of true, the pads could rub, and that is very annoying.