I assume everyone who bumps up from the stock 1.5" exhaust valve to the 1.6" valve, adds a hardened valve seat insert to the exhaust side? Even with the later heads that have a heat treating to harden the exhaust seat on the casting, this surface process will be removed during the enlargement and so will not be hardened without the insert, correct? And the water jacket around the exhaust on all non-integrated head castings leaves enough room for the extra removal of material around the exhaust seat?
