-NPC's can see further and hear gunshots/screams from farther away
-Guards see through your disguise much faster and are more lethal in combat
-You will be docked more heavily for leaving evidence behind
-Notoriety is harder to get rid of
To install, unpack the .rar file. Drag the unpacked "Scenes" folder into your Hitman Blood Money folder located in either Program Files or your Steam directory. Let windows replace all the files you just merged into the game folder.
If you don't have Steam, backup your default Scenes folder before doing this. Otherwise just use Steam's "Verify Integrity of Game Cache" feature to restore your game.