I appreciate that. The head was rebuilt just a few hundred miles ago. It had 3 burned exhaust valves. We just had a basic valve job done at the time. The machine shop elected to knurle the guides as they were "iffy" and installed new valve seals as well. I would have elected for new guides if he had called me first, but I'll address that when we have it back down. Unless the new valve stem seals have failed in 200 miles, but I don't know. Knurled guides never made me comfortable from a long term stance.