According to Fred's guide, If the engine speeds up whilst squeezing the pipes you have a leak. When I squeeze the pipe circled in the picture the engine slows. Is this a leak? Also, should air be travelling through the 1 way valve in the direction shown?
Cheers...

Normal as this is the crank vent - air travels from the top of the engine to the intake manifold but not the other way on boost if the 1 way valve is working.