I hope this clears up matters..........
1) the gen 2 & 3 turbo rails are slightly different but both are designed for side feed injectors. You can buy these injectors in various flow ratings and they just drop in
2) the gen 2 & 3 NA rails are designed for end feed injectors and you can't swap this for a Turbo rail, or vice versa, without a lot of mucking around.
3) boring out the rail will allow enough fuel flow capacity for anything that is street driven.
4) a minimal improvment in flow to each injector can be made by converting to double end feed and using the cold-start injector port for the spill-back line. IMHO this is a waste of time on an engine with a stock ECU