Less horsepower with aluminum heads unless you bump up the compression. Thats the idea with aluminum heads along with hardened seats although they will flow more than stock heads.
Completely false... 100% false... an old wives tale....
Complete bullshit.
Tested & proven over and over again.
@72DMag
Saving weight, in this case, approximately 50 lbs. Translates into at best, 1/2 a tenth. And only in a well sorted out set up that is consistent.
Now how much better is one head Han another is mostly found in the differences in the heads flow rates as well as port volumes and cross sectional area.