$.$ Neglect minor losses $($i$.$e$.,$ don$$t account for valves, elbows etc. $$

just major head loss$).$ Assume a water flow of $2$ gallons$/$minute and for your Bernoulli Equation

calculations use friction factors of $0\mathrm{.}075$ for the original $$rough$$ pipe and $0\mathrm{.}045$ for the potential

replacement $$smooth$$ pipe.