[Nuke427]

You stated you have a Cobra intake and 73mm intake tube. Do you also have a larger throttle body? My old car, set up similar to yours didn't pull very hard after 5k. I installed a Edelbrock RPM intake and it helped but not much. I then installed a Trick Flow elbow, didn't see any change. Then I installed a 70mm throttle body and the car not only pulled extremely hard to redline, you could hear the air getting sucked into the intake. It was the limiting piece in my setup. End result on modifications is as follows (Which pulled to redline hard)
RPM intake
RPM heads 1.90 valves
E303 cam
70mm TB
73mm TF elbow
30lb injectors
Crane 1.7 rockers
Pulleys
BBK headers
No cats.