[satz]

Does the left side exhaust valve need to be closed for some reason (by design)? Does it help with warming the engine faster, or reducing emissions while engine's cold?

Or would the exhaust cause a drone if you force the valve to be open all the time?

Is there any mechanical way of trapping the valve open? I remember on the E90 335i, there were a couple of mods involving the vacuum activator line for the valve...