1. as what has been already stated stock rail is fine,.. Sh!t u can run 400rwkw +++ through it if u wanted
2. Dont need the regulator unless your keeping the stock injectors, people use the regulaters to pump up the rail pressure when they need a bit of extra fuel to get them over the line
3.Stock fuel pump is big enough, but as a safety factor get a new one to feel better (youll probably end up replacing it sometime in the future anyway) as a reference nsimo will support 400rwkw for any future mods
4.if ur goin to buy injectors, have a look around the forum for a good set (see if u can get a set that have been tested and cleaned ie spray pattern,flow etc) i sold my nismo 550's for $500 bucks from memory
5. as i stated in the other post check out rhdjapan.com, they sometimes are doing deals on sard injectors, got my 800's for $660 plus delivery