Nicks Garage 383 build

I watched the video but I must have missed something. What was changed that necessitated the valve reliefs? The Bullet cam was reinstalled which didn't need valve reliefs, the block doesnt look resurfaced, the heads don't appear to be resurfaced, the valves don't look any different? Old Weaky seems to have picked up a bit of power--Why? Reading some of the comments it seems some people are under the impression the valve reliefs are the reason for the change in power. Was there other changes made that I skipped over? J.Rob