I have read LOTS of theory on this subject, most all of the 10-1 iron head engine street strip I have built even with the proper quench had detonation issues on 93 pump , never have I done a back to back comparison of Alum vs Iron heads, my last build that is in my 4100lb 68 Charger has Alum heads, .035 quench 9.7-1 com, VERY mild build, & it makes more power than I thought it would, 11.04 @123, 3.54 gear real street car drive it across the country with the ac on, I can run 87 pump & have never heard or seen any sign of detonation,my opinion is alum & steel heads make the same power.