Know what you mean the ST engine is very tame when down low have you tuned the throttle body dose a bit better with pick up ,and how have you routed the cold air feed to the filter? also thinking of a very light fly wheel myself as I think the engine lacks good pickup from low revs its only fault I would say ,and also if you fit the fuel reg thing you will find fords adaptive fueling will just dial out the extra fuel it detects.