Quote Originally Posted by NightHawk View Post
So with the hard seats I can leave the iron heads, correct?
If you have hardened seats you can run the iron heads with unleaded fuel, but if you opt for aluminum you can push your static compression ratio about one point higher without needing to boost the octane rating. The aluminum heads will dissipate heat faster, transferring heat of combustion to the coolant more efficiently, and if you're careful selecting the new aluminum heads you'll likely get improved flow, too.