You already have coilovers. Coilover is a term derived from the configuration of a coil spring over a damper, as opposed to leaf springs with dampers or indeed coil springs somewhere other than over the dampers as per Skoda Octavia etc.
I assume you mean those adjustable boy-racer things with an aluminium ring which screws up and down the damper body to vary the ride height, rather than a solid spring seat?