Replacing everything is way much better if you want anything else but looks. Take a look at he KW coilovers (even novitec uses them and sells them rebranded), you can also adjust height and stiffness, or if you can go for v3 you could adjust a whole lot more - tho unnecessary if you don't go racing with it. KW v1 or v2 are IMO the way to go, even if they prolly cost 7-8 times more than springs alone
You could also try to find the original TI springs - I hear that only the springs are different from the normal versions - as they lower it only about 20mm instead of the 30-40mm that other brands spings do.