Consistent with my plan to feed coolant through the center side frost plug holes to improve cooling to the cylinders with side by side exhaust valves, I had Cometic gasket Make these custom Mls head gaskets that have enlarged and slightly relocated coolant holes on the lower four coolant passages. Note the two center coolant holes are changed from stock as well as one small added 1/8 inch hole over the normally closed 1 inch coolant hole. My block has the two large upper deck coolant holes restricted with a threaded pipe plug with a 1/8 hole. The 1/8 hole in the gasket is to match the restriction of the pipe plug equally on both side. This will force almost all the coolant to flow past the exhaust valves with the coolest water first flowing to the center two cylinders where the engine is hottest. Cometic allowed me to revise the placement of the holes many times to try and optimize the location before I gave them the go ahead to make the gasket to my liking. The price they charged me was $89 dollars each. These gaskets now have a custom part number with cometic under my name. So now anyone can buy them if you are interested.