I used them and they performed OK - I had to tune with power commander to get it back into the stock /SE performance zone. They had a very agressive sound and were moderately or pretty loud. The standard Harley crowd seemed impressed and they sounded quite mean on the drag strip.
I have a slightly used set (less than a month) that I will sell if you are interested - biggest issue is type of sound that you are looking for - the D&D's tend to be aggressive sounding compared to VMod -stock or SE's. I ran 5 differant configurations and finally ended on SE VMods because they are the quietest/mellowest of the "louder" set ups - personal preference. From a performance perspective I could pretty well work with any of the set-ups and get similar results. What many people do not understand is that you could use the race tuner on stock pipes with the SE airfilter and tune it to similar performance levels to any of these other setups...but they would be quiter than most people like - and they would not sound as powerful - a major element in the seat of the pants dyno.