I was running a van turbo with 160/30 injectors. The 364.5 made a WORLD of difference. I never used the tow tune, kept it on 80hp/economy. At 1800RPM it felt like the turbo was directly connected to the pedal and EGTs were never a problem towing a 40' toy hauler. My gearing and tire size put me...
I would do the turbo first, then reevaluate weather or not you need more gear. I went 4.30s, upgraded injectors, upgraded to a 364.5, then went back to 3.73s.
In the product description they state that they see between 25-50hp increase with their stage 1 nozzles and 75-100hp increase with their stage 2 nozzles. Those numbers are similar to 30% and 80% nozzles.
Has anyone tried out DDPs new nozzles? They're claiming their 15% nozzle produces about the same as a 30% nozzle. Their 25% nozzle looks comparable to an 80% nozzle.