There are friction losses in the tube, and turbulence in the crimp bends. Those lead to flow losses, which lead to power losses. I'd use 3" (almost twice the cross section area) abs plastic tube, maybe sch20 or thereabouts wall thickness. Much slicker than steel, too.

Gonna be tough to use a larger hole saw on that hole unless you mount a block of wood to center the pilot drill.

Not responsible for advice not taken...