vēer, I've been trying to build the optimal light for underground surveying use (my original thread here). I'm looking for a light that has a wide hotspot, good long throw, long runtime, with as little weight as possible. 3C cells powering an XP-G seemed just about ideal. Should get about 3.2 hours on high from 4500mAh NiMh C cells (crew would carry a spare set of cells to make it through a workday.
Also, this DX heatsink module fits the throat of the C Mag with some grinding/filing. Here's a link to a CPF post by Techjunkie: "Built: The Everyman's XML Thrower" where he used this combo. I don't know for certain that this is the same module used in that post, but most likely it is. On the DX product page, if you click to "read all 6 reviews" you can scroll down and find a review written by Techjunkie which contains some instructions. I then took Chicago X's instructions and filled the heatsink with pieces of 4AWG solid copper wire and solder.
I do plan on doing a complete build thread about it, but I am not quite ready yet.
-Garry