Constant shimming, hard starts , hard to start when hot, losing compression . The common issues is the titanium valves have a special coating on the face , the powdered steel seats in the head get harder as they are run longer , and usually start to flake , the heat transfer of the stock seat material is no good. Best upgrade of seat material for these heads are c630, moldstar 90 or beryllium copper. This will eliminate all of your premature valve issues and end the having to constantly adjust them. We run this set up in all our engines with little to no wear. Best upgrade for the guides is the bronze manganese material. We have access to kibblewhite valve, wiseco (who bought out exceldyne ) del west and ferrea valves. We can also offer stainless swap kits which will also Eliminate your valves issues but you will lose around 2hp and some rpm’s. With stainless we can keep your stock seat material but your seats will need to be recut and vacuum tested to ensure a adequate seal, we use a valve concentricity gauge after the seats are cut to ensure correct valve/seat to guide concentricity. If you have any questions feel free to ask.