Yes you can do the same for the RAM after you finish the CPU, but remember the RAM speed after reaching 1600MHz won't have that impact on performance that much.

The jump from the 1333 MHz to 1600 MHz in Performance is bigger than from 1600 MHz to 1800 MHz.
So try not to get too greedy with RAM, Also the QPI/DRAM voltage has an effect on stability when you reach high RAM speeds.