Plumbing question

[Mech Eng]

Reducing the output from 2" to 1-1/2" will cause the pump to work harder to pump the water up. The further away from the pump the reduction is the better.

Putting a reducer in is equivalent to increasing the head pressure and will greatly reduce the flow rate. From 2| to 1-1/2" pipe you will reduce the max possible flow (at the same pressure) by about 40%. (flow is proportional to pressure x area)