I don't know I think the minimum is just checking them out make sure there's no sticky valves or leaking valves... I think of valve job would be the next step in Improvement.. but we have no side by side comparison on that either just gurus with flow charts...
Gee, I think the machine shop guru will find tight or loose guides when they take the valves out for the valve job. The valve job is the first modification. The checking out goes without saying.
