that's actually wrong. by placing the extruder on the frame you gain exactly nothing in speed and introduce the complication of a bowden tube.
Which instantly makes it a lot worse and a lot slower for printing flexible materials.

An i3 has no problems with a direct drive extruder. My dirt cheap ctc I3 - with diect drive - will happily print at 200mm/s - in fact simplify3d won't let it print any faster.

There is no logical reason to move the extruder to the printer frame on an i3.