i havent had a look yet, i will go this weekend. i was thinking about making one but they have a non standard battery screw cap.
as for the filters, i havent put any on yet so i cant comment, but i plan to put a red one on at some point. but i have heard the sugnificantly reduce the range.
i think what i will do is use this one as it is until i have a bit of disposable cash (which is quite hard to come by when you're 19 and drive whilst still at college) then i will buy a tracer GL2 or GL4 and use this one as a little spotting/handheld lamp.
its rated at 120 lumens and on a winter