Hi Shaun coilovers are fully adjustable so you have height up and down and dampers for soft and firm. So you can set them up exactly how you like best. Personally I prefer to be lower as your also changing the centre of gravity but you can have them at stock height if you want as well.
TBH I dont think anyone makes sport coilovers for the SC430 so your not going to get a trackday suspension setup. My Teins where the CS comfort ones and im pretty sure the Meister R ones are setup for comfort, but have a word with Jerrick first.
Yes, the anti-roll bars on these cars are very thin. Alot of the sc430 owners on the American forums swear by upgrading the anti-roll bars. Even saying its a better option to do then changing to coilovers (if you can only do one or the other). Only problem is they are not so easy to get now.