I run a Zex dry kit with a 100 shot, and it works very well. The power is there when you want it and not when you don't. I don't think you'll be satisfied with a 50 shot for very long if at all, so I recommend starting with 75 and going from there. You definitely can go without a tune, but I recommend making sure that everything is done safely and right. A new fuel pump is a good idea as are colder spark plugs, so is a window switch for that matter.