Right now my car has a HR SuperSport + koni yellows set up. But I am start going track days (roadcourse), thinking upgrading to Coilover (perhaps KW v3/eibach R2). Will I expect a significant differences?
For tracking your car coilovers are the way to go. For a DD the Koni's and springs are the better set up. Ive had coil overs on 2 DD's and I hated them. They were just too rough. I had the KW's and some Tein's. They make your car look and handle great but for me it was to rough of a ride for a DD.