The most important part here is have you changed the fuel pressure?
Are you using the standard fpr or have you fitted an aftermarket unit that is adjustable?
My belief is the limiting factor to how much fuel will flow is still the injector. The only 2 things that will affect how much fuel the injector allows to flow is the duty cycle (how long it opens for) or the fuel pressure 'pushing' the fuel in when it opens!
Yes, new larger fuel rails mean there will be more volume of fuel in the rails waiting to be injected but this will only help in terms of recovery(just a larger lake as in Asstuna's analogy).
At the end of the day, it never hurts to get your engine tuned but I believe you will be okay as is as long as the fpr is the same.
That's my opinion and I have built a fuel injection system for my old Ford that used to run on carbs. I did however get that tuned not long after building it. I did break the engine in on a generic tune though
Hope that helps?