my vote goes to bc coilovers,half the price of teins and more compliant. get a whiteline antilift kit fitted at the same time then a proper setup by hypertech or progrip(both in bonny bridge) or similar and youl be amazed. after that you can do anti roll bars,drop links,strut braces etc but i think youl see the biggest improvement with the first 2,also anything after that doesnt have to have the geometry redone though it could be advisable to get it checked if you feel like it.
im about 40 mm down on standard i think and wouldnt go much lower for practcality and getting into rollcentre adjusts etc