the only way to make them even semi work is to not cut the valve seats, but then the valves leak and defeats the purpose of rebuilding the head in the first place95% of Japanese part are bolt in parts with factory specifications and once the factory specs are gone they no longer work
Paul had half a Japanese catalogue in his car and it just cracked 400kw, once he took out half the Japanese stuff and went with Australian made stuff he is now doing 475atw with smaller turbos, why? Cause there are no restrictions anymore and everything works properly