The Intake manifold is also a HUGE restriction.



On the FD, most guys with huge turbos still dont make power up top because of the horrible design of the intake mani. They made the runners super long and skinny for torque with no plentium.



I'm going to make my own UIM with short runners and a plentum witha 90mm throttle body, I bet even with a stock UIM i can make power up high....