If you want some users to bypass proxy and disable logs for these users:

add to the /etc/rc.d/rc.firewall.local

iptables -t nat -I PREROUTING -m iprange --src-range 192.168.0.1-192.168.0.10 -j ACCEPT

Dont forget to change 192.168.0.1-192.168.0.10 - bypassing ip addresses.

Reboot router or restart iptables.

If you want to view changes:
iptables -t nat -L PREROUTING