The brightest drop-in is the
Terralux Cree drop-in at around 100 lumen(about 60-70 out the front).
Quick LED 101:
The "newer LEDs"(Cree XR-Es have been out since last year), the Cree XR-E(P4-R2 bin), Seoul P4, and Rebel 100 LEDs are at least double the efficiency of the Luxeon I, III, V and K2 LEDs. So for the same power, the newer LEDs will produce twice ore more output(or the same or more amount of light if compared against the Luxeon V, the Luxeon V has about double the Vf so uses twice the power).
So for any mod, aim for a Cree/Seoul/Rebel LED.
The brightest mod for the Minimag that I can think of is one with the Cree R2 and the
Badboy 750mA step up circuit. The main problem is the R2s are very new(probably some Vf and tint problems) so I'd stick with the Seoul P4s(the Rebel 100 tiny and hard to solder) for mods.
Also check
this thread except now use the Seoul instead of the Luxeon.
:welcome: