diff --git a/setup.sh b/setup.sh
index 657792e..6c6de87 100755
--- a/setup.sh
+++ b/setup.sh
@@ -21,14 +21,11 @@ ERROR=false
 typeset -a PKGS
 PKGS=(
     "alacritty"
-    "dunst"
-    "fish"
     "i3"
     "i3lock"
     "i3status"
     "jq"
     "lf"
-    "picom"
     "rofi"
     "startx"
     "tmux"
@@ -85,6 +82,15 @@ COPIES=(
     ".gtkrc-2.0"
 )
 
+typeset -a SYSTEM_INSTALLS
+SYSTEM_INSTALLS=(
+    "sysctl.d/99-gaming-perf.conf"
+    "sysctl.d/99-network.conf"
+    "tmpfiles.d/99-gaming-perf.conf"
+    "udev/rules.d/99-perf.rules"
+    "ssh/sshd_config.d/sshd_harden.conf"
+)
+
 typeset -A SYMLINK_MAP
 SYMLINK_MAP[zsh/rc]=".zshrc"
 
@@ -258,6 +264,58 @@ copy_all_items() {
     done
 }
 
+install_system_file() {
+    local rel src dst dst_parent
+
+    rel="$1"
+
+    if test -z "$rel"; then
+        error "missing path argument:"
+        error "$0 $@"
+        return 1
+    fi
+
+    src="${SCRIPT_DIR}/etc/$rel"
+    dst="/etc/$rel"
+    dst_parent="$(dirname -- "$dst")"
+
+    if ! test -e "$src"; then
+        error "the following source path does not exist:"
+        error "$src"
+        return 1
+    fi
+
+    if ! sudo test -d "$dst_parent"; then
+        echo "Creating parent: $dst_parent"
+        sudo mkdir -p "$dst_parent"
+    fi
+
+    if sudo test -e "$dst"; then
+        if sudo cmp -s "$src" "$dst"; then
+            return 0
+        fi
+
+        if $FORCE; then
+            echo "Overwriting: $dst"
+        elif $IGNORE_EXISTING; then
+            return 0
+        else
+            error "system file already exists and differs (use --force to overwrite):"
+            error "$dst"
+            return 1
+        fi
+    fi
+
+    echo "Installing: etc/$rel -> $dst"
+    sudo install -m 644 "$src" "$dst"
+}
+
+install_all_system_files() {
+    for rel in "${SYSTEM_INSTALLS[@]}"; do
+        install_system_file "$rel"
+    done
+}
+
 check_terminfo() {
     if ! infocmp tmux-256color > /dev/null; then
         error "Missing terminfo for tmux-256color. Try installing ncurses-term."
@@ -311,6 +369,7 @@ else
     check_packages_installed
     create_all_symlinks
     copy_all_items
+    install_all_system_files
 fi
 
 if $ERROR; then