[Roger G.]

Looking at the flow wouldn't WIS in the exhaust side increase the backpressure ? If so then it's probably better for a straight open exhaust to spray water in at lower rpms to increase backpressure and therefore toruque in the low end. I'd also would say that this doesn't help in spool up time for a turbo as the pressure differential before and after the turbine wheel causes it to spool. The less restriction after the turbo the better the spool up.