Hello, My MacBook Pro has 2 x 2GB of DDR3 at 1067 MHz speed each. I was thinking of replacing one of the both by a 4GB DDR3 at the same speed or 1333 MHz to have a total of 6GB. The apple technical specifications for my mac sais: 2GB (two 1GB SO-DIMMs) or 4GB (two 2GB SO-DIMMs) of 1066MHz DDR3 SDRAM; two SO-DIMM slots support up to 4GB That means that I can put 2x 4GB ? What are the compatibility I should look out for besides the memory socket type SO-DIMM ? Would this model work http://www.tigerdirect.ca/applications/SearchTools/item-details.asp?EdpNo=7101495&CatId=4153 Thanks for reading !