unsprung weight is relative to sprung weight, so it would slighty assist the springs and shocks to hold the tires on the road moreso on our little sunnys then say a comenwhore, but unless youv added a lot more weight with a big modern turbo engine most ventilated disc mods are mad overkill anyhow. but you be best if it was of great consern to use a two peice rotor with an alloy iner.