Increasing headshot damage multiplier.

So Im running a private TTT server to play with my friends every weekends. Im using TFA Base Redux and some TFA weapons but I realized that some of the weapons are useless in-game like some pistols. I want to somehow modify the headshot multiplier on the server so that headshots kill most of the time or if not always. Because using a silent weapon and killing your victim in 1 shot is priceless when in a small map and cant risk letting other players hear you. So is there a way for me to modify the headshot damage?