I'm going to chime in from a different angle. The question for the thread starter is: are you sure you want/need to powershift? Powershifting is great when the tires are hooking. However, if you're running on stock (or less than sticky) tires, a powershift can cause a prolonged chirp, especially on the dragstrip, costing you e.t.-wise. I'll leave out the, "it's not great on your transmission and clutch" part, which we already know.
Not saying an aftermarket shifter wouldn't HELP or make it EASIER... But it's all skill. 
