to redirect the exhaust flow from the original flow to shorter exhaust flow.
So , like using straight piping without muffler la after the valve open coz the air will go through the new hole.
Good info for skyline turbo...can this be done here in malaysia?
http://www.billetturbochargers.com/Turbo_rebuilds_and_hiflows.ewshttp://www.billetturbochargers.com/Turbo_rebuilds_and_hiflows.ews