I just tested my new Tuff Skins antenna on one of my DC-40s and it greatly improved my range,. I was impressed. But to be fair, I had also added the 16" flexible antenna to my new 320. But my other DC-40, with the factory antenna, was the only one that I dropped signal on. The DC-30s, with factory antennas, all kept a signal at about a mile, which is far as I drove from the house before turning around.
And FYI, I put my Astro 220 up for sale on Ebay. Just got the 320 in for Christmas, no longer need the 220.
The real test will come this week when we put them on the dogs on a hunt.