Took the car to the dyno yesterday. It made an additional 25 ft-lbs of torque for 375 at the rear wheels, and 10 HP for 325.
The torque increase was huge between 3500 and 4500 RPM with the peak occuring at 3800. Peak HP is at 5400. The gains completely disappeared after 5000 RPMs, as the old graph overlays the new graph from 5000 up to 6000 RPM. I'm happy with the increase in torque, but I was hoping to see a flattening of the torque curve out to 5500 RPM. The engine ought to pull like a beast out of corners which is good for my home track. I'll just continue to shift at 5700 to maximize acceleration.
Pretty sure there is a restriction in the intake manifold. I'm using the Typhoon intake from Professional Products. It has been ported to match the Canfield heads. I was told that the long runners in the GT style intake manifold causes a stagnation in the runner at higher RPMs. The engine builder suggests an Edlebrock Pro Flow XT manifold to get better flow at higher RPMs.