I wasn't trying to imply that it couldn't be tested. I just wanted proof that THEY had, and real world numbers, not just a blanket statement of 30#s.
Personal experience on my own cars has shown me that iron is not the enemy of compression.
So you are saying you'd tell someone with aluminum heads they can run 11:1 on pump gas but the exact same engine with iron heads you tell the guy to only be 10:1? That's wrong and crazy and the science and experience don't prove that out.
