Can it hook?

It's running like a 400-420 engine not a 500hp deal. I believe the converter is not working well. The slip numbers should be in the 5% range.

IMO, if you were losing 25hp from fan drag and hot air I'd be surprised. Full exhaust lots of times is beneficial. It's acting as though it's losing 80-100hp.

I'd spend time figuring out why the MPH is weak before throwing more $ at it in the form of intake/cam changes. If it really makes 500, it should run bottom 11's easily with MPH in the 120 range.