Contrary to what others tell you, I'd say stick with the SPT.
I've driven kartboy STS's before on my old 04 WRX and I personally think the SPT is a better product. I have the SPT STS on my '11 with the STi Duracon Shift knob and love it. Shift are very crisp and noticebly shorter than the stock shifter. The overall feel is very solid as well. The SPT dosen't signifigantly reduce the height of the shifter so it won't have that ultra low look so if you're going for that look you may want to re-think your decision.
You're going to love your new car. It's going to blow you away.