Gerald said it is the 480. It sounds to me like the HOT cam and not the ASA cam. No exhaust leak that I can detect. I believe Gerald fixed that.When I tuned that rig on the lakebed for 2013, it had an exhaust leak - do you know if that was fixed? It was causing it to hunt for an idle (surge) and die sometimes. Surge is a lean condition. Lean can cause a hp loss.
Also I think it was a 376/525, not a 480?
4502 had a solid ~600 hp motor in it. With a crap tune it put 330hp at the ground - 400, Atlas, 9", 5.13's and 37's. I say crap tune, because it couldn't even drive off the rollers without backfiring after he was done.... Not sure what it would do after I fixed their f'ups. I put the tune I had in it before the dyno session back in and it ran like a champ again.
From what I have been able to research about the LS HOT cam, is that they tend to have a lot of idle surge and it is hard to tune out. What has been your experience? Not sure why there would be a lot of tuning problems with the HOT cam in that the durations are very mild and the 0.525 lift is less than the stock LS3 cam. Maybe it is the 112 LSA? Pretty sure the LS HOT cam is not the optimal cam for an LS3 since it was designed originally for the LS1 and the LS3 heads have a lot different flow characteristics and it has 29 more cubic inches. The ASA cam seems to be even a worse choice as it losses a lot of low end torque compared to the HOT cam.