HI I have a vs series 2 statesman with a factory L67 supercharged 6, the mods are as follows 10psi pulley,cat backs,extractors,msd coils,9mm leads and 69mm throttle body,which is run only on premiun unleaded , the problem is it makes power one day and feels like a slug the next reguardless of daily temperature,I have replace every thing from plugs to o2 sensors, fuel economy has improved drasticaly ,but the power is only marginal most of the time compared to other days,where it would light up the tyres quite easily ,I would like to gain some bottom end and mid range throttlle response and power ,finaly I have checked all vacuum lines and hoses on the motor everthing is working,but I know these motors have a boost activator that runs to the by pass valve on the supercharger could this be the promblem?