With super low and ultra low springs,they are both probably illegal,you need a 10 cm clearance under the lowest part of your car(not sure if this excludes the exhaust system)for it to be legal... FE2 springs are the go,you can buy them brand new from holden for around $50 each front and back(live rear axle).The car will sit lower,but wont be that low that it ends up scraping an everything,and stuffing up all the underside of the car,Ive noticed a lot of guys who have heaps low springs fitted,end up with lots of rattles in their cars too,probably caused from the harsh ride from the low stiff springs...also you dont get bump steer from FE2 springs either unlike some lower ones..Its also worth buying new front struts and rear shocks at the same time,the rear shocks I use are monroe wylie heavy duty gas,which are about $120,the new FE2 front struts were about $99 each last time I bought some from the local holden dealer.If the car still feels "loose" after fitting new springs and struts/shocks,Id look at the bushes,Ive found the nolothane brand bushes are excellent,these make the car feel heaps "tighter" then the rubber bushes do,so it feels a lot better to drive,more direct in the steering and under braking,just way better all round.Some people complain about getting too harsh a ride from the urethane type bushes,but theyve probably got heaps low springs fitted as well.Ive found that with the FE2 springs,the nolothane bushes match them perfectly.I just need some adjustable swaybars now to dial out the understeer and get it handling neutral.