I didn't know the GSR had 2.6 turns lock to lock. I have an RS2 with the 2.2 turns rack (that explains the go-kart joke), and I can tell you the rack is fabulous. You drive the car with the wrists, and you never need more than a couple of degrees of opposite lock.
I do not know the cost for you to change it, but I give my thumbs up for the 2.2 turns rack
Tarik