[Shane@DBPerformance]

5% or less is excellent. 10% or less is what you want to see. 15% is starting to get to the point where something might need to be fixed eventually. 20%+ is often noticeable power loss. It depends too if it's just rings or if it's a valve problem. I have had Evos in with 5% or less on 3 cylinders and 1 cylinder in the 15-20% range due to a bent or non sealing valve that lost 20whp on low 300whp cars.