x2 :thumb:OBS PSD's have large exhaust housings, and take some rpm's for the turbo's to spool. Couple that with compression around 17.5:1, and the IDI with 21.5:1 compression allows the IDI to eat an OBS on the bottom end. The PSD's lower compression is offset by higher boost pressures, but because of the large exhaust housing, it takes a second for the turbo to fully spool up.
N/A Diesel's will always have snappy off idle performance due to their compression.
Anymore this is how I think of the 7.3IDI vs. PSD debate goes for me. If I wanted a truck that I would use for work (think like ranch truck, always has crap in the bed, dont care about body, etc) I would get the IDI. If I wanted a truck that has a potential to make good power, I would go for the PSD. If I did buy a PSD, I would buy a nice one, therefore not use it for work (hauling is ok, but not like the work above^^^). I feel IDI's can take much more abuse and keep going than a PSD. And even if they cant, used IDI engines can be found for way less than a grand.