DDR Sticks aren't like you think they are. Timings can be set very low. It doesnt normally matter if the stick doesnt support that timing. Its just getting your ram to work at these settings that is hard.
Firstly, Micron modules are excellent. If your ram has these modules expect a decent overclock.
Secondly, voltage will help your ram go further. You may need protection in the form of heatspreaders to keep the rams life expectancy high.
Thirdly, if you ram does not work at the high speeds, windows will tell you. By this I mean registry failure, BSOD's or lockups.
Upping the ram voltage does a lot. Like I said, I can hit almost any FSB with the voltage at 2.9v