Scott,
I have no personal experience with the D66 although I wouldn't mind if someone gave me one to test
.
On paper, it looks like it would fit my needs perfectly. After much research that I did with my 01 7.3L, I figured out that the TN JB turbo would be a perfect match for me. It was. I loved that turbocharger regardless of the bad things people had to say about it. It worked spectacularly on my truck and did exactly what I needed it to do.
The D66 is equally as impressive-looking by comparing it to the stocker. The increased airflow on the compressor side is exactly what the OBS trucks need when running modified programming (smoke with no power increase).
If I can bring myself to end my debt-free status, I'll probably order one up one of these days. It will either be that or I will upgrade totally to the 99.5-03 turbocharger setup and install a USA turbo in this truck too (TN JB knock-off).