I installed a Kartboy shifter and bushings in a car with the STi setup (SPT really I think they are the same. I took some pics of the Kartboy, STi and OEM RS shifter and bushings side by side. Basically, the STi shifter looks a lot like the Graham Good one. The tail piece is longer than stock one. When I say tail piece I mean the part from where the bolt goes though to the ball socket. The STi and Kartboy essentially had the same tail length. The part above the where the bolt goes through, the shaft, was much shorter with the Kartboy and the STi and OEM being almost the same length. The STi is a little shorter but not much.
The bushings for the STi look exactly the same as the OEM one. The STi may feel ever so slightly firmer but not a ton. The Kartboy bushings feel very hard, essentially the same as the Cusco bushings. You can probably push a thumbnail in the material and make a mark that will disappear.
I have pics that will eventually end up on the AZScoobie site but, I'm not sure when. I'd say I'll send them to anyone in advance but I'm not at home right now and I'm not sure when I'm returning. I'm kind of in the hospital now with stinking pneumonia. I finally feel well enough to sit up and read. At least I have the I club to keep me company when my visitors leave