A dedicated forum for discussion on all things relating to Jeremy Phillips designed cars. Including the Star, Leader, Striker, Phoenix, Fury, Jester, Stylus, Mojo, Riot and the Full Bodied Riot.
I understood in conventional orientation, they took air in with minimal disruption to the airflow behind them but if fitted "backwards" they sucked air out due to venturi effect, again with minimal airflow disruption.
In its normal use the sharp edges act as vortex generators that help the air through the duct overcoming the problem with the slow moving boundary layer. Reversing the flow direction will not result in the same helpful behaviour.
It wasn't designed for exhausting air, so although it might do something it is inelegant.
Bit like using a cordless drill as a hammer. It may work, but it isn't right.