Any time you update your ROM, you will loose the kernel that you had from the previous ROM. Say, if the dev decided to include a different kernel for whatever reason, Or if you had a custom kernel previous to the update. Just find an OC kernel that takes you to a higher OC and flash it. MOST devs are finding that OC's higher than 8-900mhz cause more problems than they are worth. Also, the newer ESE53 2.1 roms are WAY faster and usually require less OC in the first place.