KR is pre-detonation in your cylinder. Meaning it ignites before it should and can cause a chipped piston. On a stock car 5-7 should be ok but on a modded car you don't want any. To get rid of it you need to have more airflow out of the motor. If you are moderately modded you need to tune it out along with breathing mods.

http://www.zzperformance.com/blog/kr-how-to-fight/

http://www.zzperformance.com/blog/eliminating-kr/

http://www.zzperformance.com/blog/ab...ock-retard-kr/