corsair memory with the term "DHX" in it's name should have micron, but you will pay upwards of $250 for the set. or you can get 4 sticks of crucial ballistix for less than $120 with guaranteed micron, since crucial is owned by micron.
Ballistix are NOT available in 2X2, anybody know why?
They don't make a high-overclocking Micron D9GMH or D9GKX equal in a densities that high is most likely the answer.
There is not much evidence on what chips overclock best from 2x2GB configurations from what I've seen on the web, and if you get Micron D9s, it won't even guarantee you much for the reason I stated above. Just like not all 1GB density Micron D9s are crazy overclockers, not all of the 2x2GB kits will do well.