my s1 will not boost properly it`s got a bleed valve on it{which i hate}no matter which way i turn it the boost does`nt change just stays at half a bar i`v taken the plugs out which were black as fook .i`v only had the car 2 months it came with a graph showing it was running 1.7 bar and 198 bhp i`v not changed anything on the engine at all all help/advice appreciated