I agree, sidelights are very poor, so I upgraded to canbus LED ones which are much brighter (and therefore make you more visible in overcast conditions).
Of course, once the sidelights where changed to white LED, the main lights looked far too yellow so I also upgraded those to equivalent xenons - but this was mainly because they look whiter and are a closer match to the LED sidelights rather than me wanting anything "brighter". I think the stock bulbs are bright enough (on a sidenote, I don't think an HID retrofit would be worth it cost wise)