Why exhaust valves should always be ground and....

and the seats cut. Pictured is an exhaust valve from a Subaru Legacy 2.5GT. Not all the valves were this bad, this one was the worst. Notice how bad it's "dished".

Now it's just touched with with the stone to show how badly it really is.

Not that it's ever really measured due to; you only remove what's necessary... buuuut for those who are curious, we took notice to the gauge.. About .010". The other exhaust vales were about .004-.006" and intake about .003".