I've had mine lower that than on D2's, once it's that low you can't turn lock to lock on the RX7 wheels without rubbing the inside. Also at that height my GT-Spec underbrace was about 3/4" for the ground. Needless to say it isn't show quality anymore.
Look at step 8. To lock the springs into place, you have to adjust the two round "dials" (i don't know how else to describe it). For the Ksport's, those two round dials are black and plastic. At least on mine it is. You can do this while it's on the car.
Take speedbumps one corner at a time. Take them diagonally in other words. So just one tire passes over it at a time. Unless they're really high speedbumps. I love that height. I'm having to get coilovers soon, stock struts on lowering springs for 70K + at the moment hehe, and when I do it's going to be that low. 4 wheels tucking is what I want. hahaha