If going over .030" you'll definitly have to have the domes rechamberd,it's shape has a huge affect on the swirl and port flow and you will definitly see the powerband fall at the top end. I would recommend use a 50-50 mix of 110 octane and pump gas for some cheap insurance, even if staying and .025". You will also be able to run it leaner on the jetting with out chance of detonation, and it will also be less sensative to preignition. You will also be able to add more timing