Search "CREE XML T6" on fleabay. That is the LED and is capable of 1600lm, but you'll see exaggerated-claims-a-gogo. It takes 2 x 18650 batteries to get the best out of them, but the single battery torch such as the C8 or the little zoomable ones are plenty bright enough to prevent people seeing what is behind it on full beam or strobe. I used mine at MCG The Gaol last weekend and buggered up people's night vision in the dim areas a treat
These for the C8 and they only come in pairs this cheap @mo, but many C8's come with 3 mounts. Or for the short zoomable one you need a 30mm mount and either half an inner spacer or some tape. I use one similar to this, and on my 2x18650 long torch, one of these. You can use part of the inner plastic ring from LX tape as a spacer, or a strip of the black plastic from a microwave meal works well also.