Fark no! Yer lets put in a box that makes the car slower... Makes total sence. You'll never smash gears in your Neanderthal cog swap box as fast as you will with a tricked up auto, go and see a good auto place (I used a&t in toowoomba and they were excellent) and get a good firm shift kit set up with a small stall converter (or a large one, I personally now wish I put in a 4g converter). Now line up the gear monkeys and laugh your ass off as you leave them in your wake (yes that is a boat joke)
Come for a drive in my car, you'll never want a dirty flat capper box ever again...