Just stay away from APC and other's like that. Skunk 2 is good, anything reputable. I used Energy Suspension Shifter Bushings and lubricated everything well. It shifts smooth like stock.

One thing to understand is that a short shifter works by increasing the distance between the stationary "ball" and the attatchment point to the shift rod. This gives you less leverage, and increases effort. The amount shouldn't be increadibly noticible.