Well unfortunately I think my valves are tight again at 10,000 miles. I had them adjusted at 6,000 and it looks like it's happening again. So far this season I've noticed the cold start up RPM's slowly dropping to the point yesterday it actually died for the first time while warming up. Haven't seen this since last time the valves were tight. I'm wondering if anyone with the 16.5 or newer has had tight valves yet? The 16.5's and newer have new valve stem seals and valve spring seats as well as a different supplier for the valves themselves. I wonder if any of these changes could be for valve issues? I'm not sure if I have any adjustment left with mine or not since the dealer did it under warranty the first time and they didn't record shim sizes. Does anyone know if you can run without a shim or do you need at least some shim? If mine are beyond adjusting I'm wondering if I should order the 16.5 valve stem seals, spring seats and valves. Does anyone know if the 16.5 valve parts are exchangeable with 14-16 vipers?