Overclocking ram from 800-1066MHZ

[mrc1992]

hi i have 2x2gb Corsair XMS2 PC-6400 800MHZ ram 5-5-5-18 at 1.8v and i want to overclock my ram from 800 to 1066 and i have a e6300 pentium dual core 2.8GHZ and i am planning on overclocking it to 4GHZ and thats will take my ram to 1066 but wat timings should i set it to and wat voltage but is my ram a good overclocker or should i just do a minimal overclock