As far as I know, lightning edition is already overclock up to a higher point than boost edition. It is just terminology of MSI to define their gpu's.
Lets have a look at MSI original explanation for the terminology.... http://event.msi.com/vga/2012/series-comparison/
Lightning is the fastest of all with more feature and custom cooler
TwinFrozr is the mildly overclocked reference version with custom cooler