I bought Ahmeds' springs recently, not had a chance to try them out yet though. They are made to work with Konis and do not lower the car at all unless otherwise specified. I got Ahmed to make me a set -10mm. This is the lowest he will go as it causes spring seating problems if any lower. The car sits really nicely at this.
Also he has the choice of track and road srpings.
Rgds,
Pete.