whats the leanest cylinder?

on the stock car engines we ran into the opposite ,cylinders overheating because of poor cooling #4/6 and 3/5 even with the mods done .the coolant pushes around the center cylinders to quickly, so we cut .015 off the tops of the 4 pistons, to get them running at the same temp/fuel .on a street engine this would be help full .but not for a drag engine. our failures were in the middle cylinders mostly exhaust valve problems, swelling up of the stems and dragging in the guides and we removed the stem seals on the exhaust valves to help cool the valves, never had smoking issues ,you couldn't tell there were no seals. and the exhaust lobes of the camshafts were wore down from the tight guides when the engine went lean.