If it's just an upgrade in braking power that you're after then I'd recommend going for modern brake blocks and aero levers first (if you haven't already done so. My experiences with this are briefly described here
. Sheldon Brown also reckons
that they are worth upgrading. If, later on, you decide that you need better brake calipers as well, then you'll have some lovely new levers and block to use them with!
Thanks, but I fitted cartridges when I got the bike and, as noted above, have just fitted aero levers.
As well as the notable flex in the calipers, I'm fed up with not being able to centre them (or if I do they don't stay that way).
I'm going to give long drop Miche Performance calipers a go: they are only advertised as being 57mm, but they've been measured by a couple of people who have them, and they are close enough to 65mm for me to gamble £20 on.