Changes

This question comes up quite often. The answer is whatever you are most comfortable with. Some people don't want to see any KR. Some people say anything up to -3 degrees in 2 cylinders or less at the same time is ok. Most would agree that -4 or more is not a great idea and one should remedy that. Some cars seem more prone to KR, some have KR at specific RPM ranges that can't be removed with meth or even full E85. You might see one cylinder in particular that has more KR events than the others. Every motor is different. Use your own comfort level when setting timing.