A couple of advices.
Forget about DMZ, UPnP and the big list of ports to be forwarded.
You only need to forward 3074 UDP to have open nat. That is the only port you need.
Sometimes even with that you have moderate connection. Some routers dont forward the port correctly to your PS3 because it has a static IP and that IP is not in the DCHP router list,
So set the PS3 to have the IP automatic, and bound in your router the MAC address of your PS3 to the IP you want to forward the 3074 port. In your router you should have the option to set static IP to some devices.
Anyway there is little you can do with your connection. Your game expericne depends more in the other players connection than in your connection.
A strange thing. The day 1.0.7 was released, myself and friends I was playing with had the best connections and hit detection since the game was released we were going 70-10 in hckc all night. The next day it was like playing a different game. Since the day after patch it seems to get worse each day now.
My game gets a bit worse with each successive patch. It's painfully obvious that they are gradually swinging the advantage in one direction for some inexplicable reason. It's definitely depressing to know that you're incredibly unlucky enough to be among the minute number of players that are being sacrificed for the supposed betterment of the masses.
I would tend to agree that Lag is horrible right now. I am not sure that this is was due to the patch or the new maps. I played with my buddy who has only the old maps and there seemed to be very little lag on my end. However, with the new maps I cannot get a kill I am behind everyone on the opponents team. I shot this guy 4 times up close with the peacemaker and he turned around a one shotted me .... just horrible