The WRX comes with rubber shifter bushings intended to isolate the shifter from engine vibration. While they do accomplish this, they also make the shifting action vague and rubbery.
Kartboy bushings reduce this numbness by replacing the factory rubber with 95A durometer (that's firm, for those of you who aren't materials scientists) polyurethane.
Installation takes about a half hour of work; the bushings install under the car, and the car must be on a lift or jackstands to do the modification.
The five-speed kit fits 2002-2014 WRX, as well as 2002-2011 Outback Sport and Impreza RS.