A good rule of thumb is that the next size hose up will flow about the same as the pipe in that size. So 1" pipe needs 1 1/4" hose. Hose is more flow restrictive than piping. But the real issue is fittings. Many people go to the AN/JIC fittings in these applications. That spec is primarily for high-pressure hydraulics. The internal diameters of those passages are adequate for 3,000 psi, but are very restrictive at 30. Purpose-built automotive type hardware is better suited for these applications. Always remember, the more the fittings, the less the flow. And elbows are absolutely a mistake. You always need to use a sweeping (tube style) elbow, not a 45 or 90.