The easiest mods are to stick either a Welch-Allyn 1162 bulb or a Sylvania 5761 bulb in it. The latter is easier to find (ebay), but requires that you open up the hole in the refector just a bit.
Beyond that, you can replace the reflector and/or battery, which you'll find as radar said by doing a little search.
A textured reflector makes a huge difference in the beam. you lose some throw but it looks much better. Aside from that the Sylvania 5761 bulb is nice.
I have one that is using a 55W halogen bulb and 3 18650's, all it's good for is starting fires and melting the plastic socket.
My first improvement did throw 2,272 feet and I now have a light that beats that!
The 5761 bulb is the trick. you can run that bulb on the stock cell or juice it up to 7.1 V bulb on 7.2 V packs.
Just remember in comparing bulb lumens and torch lumens are what the bulb emits and what actually comes out of the light is 65%.