When you set the speed faster, then the timings will default to a slower speed. Your memory, if all is to be told, is probably faster running at 1333 with the lower timings that with the higher buss speed (which really makes no difference in real world use, nothing, nada, zip) and the slower timings.
People buy 1600mhz memory so they have overclocking headroom when they overclock the processor, not because the 1600mhz memory is 1 iota faster.
My god, how many times a week, or day, or even an hour can this question be asked. Guess I better go to bed, I feel like I am getting a little cranky.