A number of thoughts and hypothesis are postulated on the
benefits or otherwise on the use of RAM AIR.

DC,

 

At 200 Kts, ram air can theoretically add 2 inches to the manifold pressure - I.E. the plane is flying at 8000 feet, the engine is at 6000 feet - That is approximately equal to adding 7% more power at the flying altitude (~3.5% per inch MAP).  And, its' free. 

 

<<<<In clear and low to moderately humid air, has any pilot noticed in
increased tendency for Carb icing using RAM AIR?
>>>>>

 

A proper pressure recovery plenum should not increase the icing - monitor the temperature.  However, speaking for me, myself and I only, fuel injected systems are all that I know.  I have enjoyed the power increase from ram air and I do see close to the theoretical rise.