a hugger normally replaces the chain guard. they are not bulky and they are rather light, but installing them does require removing at least the left passanger footpeg. they bolt on instead of the chain guard (2 bolts on the left) and on top of the 2 rear brake line guides on the right side. it seems to hold them steady.
take note that unless you ride a lot in rain, or need to shave a few tenth of a second on the track doing 200 kph, they have no real function.
with the right color however they make the bike look ten times better