How to correctly choose and install a turbo blower air pipe?

Turbo blower air pipe selection is different from roots blower:

Air pipe diameter shold be bigger than turbo blower diameter. Even air pipe equal to turbo blower outlet diameter is not a wise choice.

There are 2 advantages:

1. when air pipe diameter is bigger than turbo blower outlet diameter, pipeline resistence will reduce and save electricity. 
2. it lower the noise in turbo blower house.