will upgrading the fuel system like return lines, fuel rails, higher flow pumps and what not get a NA 8 more power?

 

If you do a search on fuel pumps and fuel system upgrades there are some good threads about this.

Essentially your stock fuel system injectors are good to 300hp. Anything above that and you should upgrade. Really though without increased airflow and engine management changes fuel is only 1/3 of the power equation.