Hey, Ive also just fitted a hybrid cooler to my R33 with standard turbo, turbo back exhaust, bleeder valve, and mine does the same thing, except i run low boost (9psi), and it still jerks at high revs???? Could this mean I need to get a bigger fuel pump, or Do I need a fuel cut defender fitted. Ive checked for any boost leaks and still cant figure it out. Would a electronic boost controller fix this problem or power fc????