Stock 400 Piston Boost

I remember some video where a guy was doing some dyno test and it was something somebody posted here on this forum..
The point was to show how much timing affected actual horsepower.
It was almost crazy how much timing was taken out and how little actual horsepower was robbed...
and don't quote me but I remember it was something like going from 34 to 30 was like 10 horsepower loss.. and then down to 26 was like 20 or 25 horsepower loss out of the 400 plus... It was like he had to take it all the way under 20 degrees before a massive amount of horsepower was starting to get taken out..