Well.. the mod will give you just the shotgun and the silenced pistol, no more.
The other weapons are already avalible in the singleplayer demo if you use the cheat to get all weapons. The shotgun and the hi-standard silenced pistol are NOT included in the singleplayer demo, thats what the mod´s for.
But, I´ll guess those other weapons won´t harm you.. consider it a bonus