Yeah, a "true" short shifter would require a new linkage. It all has to do with where the axis of pivot is.
I personally like the feel of the stock shifter. The length and force required to shift is imo really nice. Maybe not the best looking shifter, but I never feel like the time it takes me to shift gears is too slow...
here´s what I do for a really fast shift:
put my hand on the shifter and put light pressure in the straight line direction of the next gear I´m going into.
drop the throttle at the same time you´re throwing in the clutch. when you throw in the clutch, use your ankle instead of your whole leg. this will make things a bit quicker. also, make sure that you let off the throttle and push in the clutch at the same time so you don´t dead-throttle it and then buckle up the wheels.
then when the clutch goes in, you´re already pushing it a little into the next gear, and the fact that you´re dropping the power to the wheels will pop it out of gear and it almost shifts itself. then once you´re in gear just drop the cluch about 3/4 of the way and then wean in the throttle at the same rate as the last 1/4 of the clutch stroke and you´re golden.