Good to see you've rose this question. How much power the engine makes is determined by how much air this engine system can flow in a given period of time. So at given boost pressure a more free flow system processes more air, burns more fuel and makes more power. It is the reason that when identical turbochargers were built, cars that ended up with more power always had a better flow engine system.
So you plumb the gate back, then exhaust flow will still be restricted by capacity of the exhaust. I've attached a dyno result from an earlier run which is External gate V External gate plumb back with nothing else changed out of a 3 inches turbo back exhaust. So in a simple answer, Externally gated system makes better power.
Older ATR43SS-2 turbo:
Green: External gate V Blue: External gate plumbed back
Hello all, I have these car parts left in my garage, the exhanst tip, stock air intake and the tie pod end are especially for the R33 GTS25.
I am planning to sell them all for $100..
Location is at south-east surburb in melbourne, better come and pick them up.
Let me know if interested, CHEERS