no.2 system used for inbound flights, and this used the stbd outflow (oops! discharge) valves.
No perf penalty, as 'Dude noted. I vaguely recall being told that the drag from the recuperator cancelled a lot of the recovered thrust. I've no idea how true it was.........
Does that mean there were port and starboard discharge valves? That makes more sense to me.
I know it sounds crazy, but that cabin air had to be dumped somewhere, and without those thrust recovery nozzles all the energy it contained would be lost, so that a net zero is actually a win!
CliveL