this is a good way to test for a faulty one way valve but shouldnt be left like it. as the apc will be bleeding metered air from the system off to atmosphere instead of back into the system after the amm. ok so it will run rich not lean so not as dangerous but not ideal either. plus if that one way valve is fault then pressure will be getting into the purge valve, charcole canister etc and boost pressure will be lost so working the turbo harder. im guessing the one way valves are a silly price from saab hence no one replaces them?
b234.5R lightened and balanced, standard turbo