An alternative, if you don't use Sandbox or any other mod that replaces sr3_city.lua and notoriety_spawn.xtbl and character.xtbl, is called Random Encounters. It's pretty hardcore all by itself, especially starting a new save-game. Random Encounters will send groupings of all types of gangs after you, they come from nowhere and don't spawn on the street. Stag, Ronin, Genki, Brotherhood...cops, aliens, strippers, sometimes a superpowered toilet/question mark/Decker soldier...it gets pretty intense sometimes, especially with STAG and the superpowered, since there is a chance you might have your powers suppressed.
The conflicts (with other mods) can be overcome easily, as Random Encounters only adds a few lines to each of the xtbl above, which you can merge easily with existing mods using Notepad++ with its compare/merge plugin (similar to WinMerge) and SR3 xtbl editor found here on saintsrowmods SR3 (tools) subforum...or even without the plugin and a little time searching for the lines to copy and paste.
There is also Hardcore Intense Mod...which includes gangs of all types as well, however, they spawn with normal citizenry and will go ballistic if you cause any type of chaos. Also very cool mod, but less compatible with lesser mods that use only a few xtbl tables edits.
There are always more options.
Good luck!
