Autolite Tuning Briggs 206

Anyone notice a tuning change with the new plug? Starting to think they burn better. Allowing more fuel vs the old spec plug. Switched plugs and motor seems off. Hearing other guys talking seems like the new plug might be making a difference. I have a spare exhaust and tempted to weld in an egt bung and due some testing during practice. Seems like there might be power left on the table with the new plug.