The best modification on our Ozzie Defender 130 is the full length Black Widow storage drawers. They lock securely, and they don't let in much bull dust. That's where we stored all of our SLR and video cameras for outback photography. The drawers are large enough that we could put padded pelican cases in them for additional dust protection. I would like a similar set up in my Defender 110 here in Phoenix. I want good security, and good protection for cameras and computers.
The other best modification was the white Autofridge from Australia. It is a portable refrigerator with a large wrap around eutectic plate. It's the only Ozzie fridge that I have found with an actual eutectic plate. I wish I could get one here in the USA for my 110.
My least favorite modification is the massive roo bar/ bull bar on our 130. It provides lots of protection for the front end, but a thing of beauty it is not. It was a great place to store sand ladders, and made a good platform for slow speed video shots with the Canon XL1. You would not want to film at fast speeds from the roo bar because you might get run over if you fall off the platform.
The Roo Bar was there when I purchased the truck. I left it alone and plan to leave it in place. I reckon that people wouldn't want to steal my 130 with the big nasty roo bar out in front. It's my anti-theft roo bar device.
After owning both the 130 and the 110, I like the turning radius better on the 110, and the available storage space is better on the 130. Both of them are great trucks.