i searched my steam directory and looked for the biggest BSP files i could find.
here are the results of the tests: (sorry for .bmp, .jpeg loses too much text quality)
As you can see WinUHA compresses BSP files the best, with 7-Zip in LZMA mode coming second. 7-Zip is probably the best, as WinRAR can open 7-z files, so you dont have to download 7-Zip to get the map.
WinUHA is available here.
Yay, useless info!
![:D](http://192.241.182.11/images/smilies/grin.png)