Aaron Cake [on his site] recommends putting grease on the actuator pivots, driving spiritedly, and then checking the grease to see if the ports come on or not. Well, does the car have to be moving? Why not just have the hood-up with the engine running and watch the port actuators as someone revs the engine past 3800?

 

if you have a s4 then you can simply take off the vacuum hose and blow in it or use a compressor. not sure if the s5 works the same.

 

You can test it by applying the proper air pressure to the tube [see FSM]

As for free revving it.. That wont work on an S4 because it requires backpressure from the exhaust [under load].

Not sure about S5, but I imagine they could be tested by free revving [they're actuated by a solenoid and the airpump, same for the VDI at 5500rpms]