A simplified, low cost, turbine flow controlling device, using a sliding gate, with an actuator to control exhaust flow to multiple volutes, which volutes have perforated transverse divider walls. By moving the sliding gate (80) from a closed position (88) through a displacement of “a” to the next position b1; and then from position b1 through a displacement of “b” to the next position c1, each a discreet movement, by a simple actuator, an increasing number of volutes are opened for flow from the exhaust manifold, via the volutes with perforated transverse divider walls, to the turbine wheel, without the attenuation of pulse energy usually seen in VTGs, at a cost lower than that of a VTG.