This just depends on what you want to do and how extreme you want to go. I have heard arguements either way. The manual does not rob as much horsepower, however, it is harder to control and get good at shifting if you are going to go turbocharged in the future. I own a 300ZXTT and the common issue with a manual is that if you go to much horsepower, you have to learn to go through the gears really quickly to you don't redline under boost and cause knocking. Stillen, a Z specialty store, recommends a automatic for people wanting very high horsepower. The manual is ok for people that just want to boost the HP to a certain limit. If you are going to keep it as your daily driver, then I would go with the manual, that is what I bouht, but if you plan on going with extreme power increases and want to drag the car, I would go with the automatic for ease of shifting and better shifting points that will not cause knocking and damage to your motor. Just my thought and opinion though. Up to you in the long run.