I have tried most including Earls, Percys and Mr gasket and prefer a brand called Remflex, not saying you will have any problems with the Percys either as they where decent, but the remflex are thick graphite and compress for warped flanges, also since they are graphite they allow minor movement with expansion from the head to the header, I had problems sealing small tube headers with a blown motor (lots of heat and back pressure) and thats what I landed with.