OK, thanks for all the info.
From the sheldon brown info I think i need to make sure they are currently setup properly first.
Good call! Although Sheldon's guide is not as good as
this and the associated
simulator. But the real pity is there isn't a single complete, accurate and easy to follow guide on how to set canti's up properly that I can see. Because canti's MA is variable, and generally a bit too high in combination with the levers, the science/logic of optimal set up is not simple, and it is fault-intolerant, unless one understands and knows what to watch out for. The result is there are lots of random advice around, chief amongst those is probably brand/model A is better than brand/model B - the fact is any canti can easily be set up poorly, while most can be set up to perform well.
Since you have Kore ones, unless I am wrong they are wide profile units (like pic below). The thing about wide-profile is their MA is generally fairly uniform, so the first thing I would advice is to: ensure: a) you have decent cabling performance (i.e. mainly outers not too compress-able, you can check by seeing how far you can still pull the lever after the pads have touched the rim), and b) pad/rim clearance no more than 2mm, which is only achievable if the wheels are fairly true.
Chance is sorting cabling and limiting pad clearance may be enough to give you decent performance (given you have good pads), however if not in your case (if they are indeed wide profile units) increasing MA can increase stopping power. I think you should be able to do so by minimizing the distance between the pad and the brake arm, by using the thinnest cup and dish washers there, which should, as you can see from using the tool in the link above, lift the MA curve by reducing the angle alpha. On top of that, you might also be able to increase MA by shortening the straddle wire. However, beware high MA has its price, and it is that the higher the MA, the less pad/rim clearance is allowed if the pads were to be able to grip the rim firmly (after cable outer compressibility has been taken up), and that more frequent adjustment will be needed as the pads wear.
Hope the suggestions above are not too confusing...
