Too much gear?

After seeing his run, not so sure it is port stall, as it's just not getting what it wants.

If a port stalls before a said lift, it just means that that head(engine) will not accelerate as quick as it could, and may not rev as high as it should.
At this point i think the the cam is requesting more lead for the op's right foot.:poke::D

from the video it did not sound as though the engine was laboring to pull rpm.
Did you notice it set at 4000 rpm when he launched? Then the rpm took off. This cam need 500 more rpm stall, but it's not seen in the 60 foot because he installed lower gears aka more multiplying of torque. so his 60' was the same but he need a new TQ. NO has nothing to do with lost mph on the top.

If the exh was the problem(it is a restriction and would make more power, just like the TQ if it was free-d up) it wouldn't want to rev more if it was the problem.