I had an SSDiesel tuned PCM that I threw in the 3500hd. I have to say that I'm impressed! I wish that I'd done before and after times but for a 9000 pound truck (with the wife and I in it) it suddenly is spunky at lower speeds. One could almost close their eyes and it would feel like a tbi 350 up to 40 mph or so or when you crashed, whichever comes first.
I did take some times just because I was so surprised, 0-40 7.8 seconds and 0-60 in 16.4 seconds. It still tops out at 13psi so I can understand the slow time between 40-60 but it does feel stronger in the butt dyno.