I don't know much about it but wouldn't you only need a new fuel rail if you need to flow more fuel than stock? Do you have a turbo or super charger? If not then I doubt you need one. You can tell if you have fuel starvation if it falls on it's face at high load high rpm's. A more accurate measure is to use a wide band o2 meter. These can be expensive but so is a rebuild from a burned up piston from running too lean. I have one of these: http://wbo2.com/ in my Vette. Gives me piece of mind that the engine is getting the proper air/fuel mix.
You don't "need" it, because you will probably be able to get by with the stock setup initially, however since you are putting on a turbo it may be something to consider once you get the turbo up and running.
I agree with what Bob said, get a wide range AFR/O2 meter to see how it is running once you get the turbo installed.
Since I think you mentioned you are installing a new fuel pump and regulator, it makes it easy to add a fuel rail later on if you already have those other parts installed.