Kind of a dead thread but im experiencing the same thing almost but im running on a stock pulley with sd headers and 3 in exhaust. Engine only has bout 2500 miles on it. i still need to put a new fuel filter on it but i dont know if that would help any. The car has just seemed kinda sluggish and my throttle response isnt the greatest. just doesnt seem like im making the power i should be but im not sure if im just expecting to much. I know i need a tune but just didnt know if anyone would have any suggestions on other things i should try? i do know i have a tiny exhaust leak to on my crossover for my headers but that should be getting fixed tomorrow