Depends on the P67 MOBO, but the theoretical CPU limit is ~DDR3-2600. Since there's no real gains over DDR3-1600 and often keeping >DDR3-1600 perfectly stable is a chore I really don't recommend over DDR3-1600 on LGA 1155. Further, those kits are generally >1.50v and both require higher voltages to the CPU's IMC and DIMMs so the gains tiny for the 'real' cost (CPU + RAM).
Unless you are 24/7 OC >4.5GHz my advice is don't get >DDR3-1600.