Mr. Lyons, YOU cannot increase pressure with pipes. PUMPS increase pressure.
OK here goes simple basic 2nd year apprentice stuff.
If you have 60 PSI pressure going through a 3″ pipe and you decrease this pipe to 2″ guess what YOU STILL have 60 PSI TA DUM
What you will INCREASE is the velocity (FPS) BUT you just gave up VOLUME The actual pressure will NOT INCREASE.
Now here we move on to 3rd year apprentice training with something called FRICTION LOSSES.
When water moving inside a pipe hits an obstruction like an 90 degree fitting its going to have a pressure drop over coming RESISTANCE just like electricity has in voltage drops over a long wire run.
Unlike Hydro nicks lack of credibility in plumming we plumbers take several factors into consideration with regard to sizing in in spite of the stumble bums advice we look at flow charts regarding the size and type of materials this liquid will flow through.
We figure developed length head (Height) Fixture unit demand measure in cubic feet (7.48 gallons) and needed available pressure for the fixture to operate properly.
Sight unseen only a guy like hydro nick could tell you exactly your pressure losses and tell you exactly what materials to use even if they are not code approved.
You should seriously consider calling a local LMP to give you a hand in picking the actual piping you need