An agricultural air cart assembly is provided with individually controlled product distribution lines which allows for balanced pressures and even dispersal of air through different distribution lines of different lengths running to different sections or row units of a seeder or drill. Rotatable fans are operatively connected to corresponding first and second distribution lines and are configured to generate optimized air flows in the first and second distribution lines which entrain and carry the product downstream toward corresponding row units at balances pressures. A controller is operable to adjust the pressures of the air flows outputted by the first and second fans by adjusting the position of corresponding fan shrouds over the intakes of the first and second fans.
