maybe someone can help me,

about once every 20 or so times i boost the car, it seems like its not making alot of power top end, most of the time it feels really strong, other times its just.. blah

it still puls hard low end, but around 6000 till redline it just doesnt feel like its puling anymore.... boost is constantly at 11 psi... tuned with aem ems tial wastegate, greddy type s bov... it doesnt mater if its hot, cold, heatsoaked... nothing consistantly.... anyone have any ideas??

 

anyone?