Razor, I dare say that yes, if you upgraded the rods and pistons to forged items then your ZE engine would be able to manage more boost, whether that means you would need or want a bigger turbo is a matter for you to discuss with your turbo supplier.
If you did replace your pistons you would be best going for a design that would give a lower CR than the ZEs as it would limit the amount of boost you could run especially if you wanted to inject nitrous oxide at the same time.
It may be worthy of note that if your engine is up to it then you can inject nitrous and run a turbo at the same time but I wouldn't try it either on std internals. It is better however to run nitrous rather than run the turbo to its limit but you have to consider that while injecting it will increase your peak boost for a while, probably quicker than waste gate can control at 1st.
I would do both if I had an engine to support it
