I'm running 80hp KAX injectors and LOVE them. When I first got them, it was a night and day difference between stock.
Power went up drastically and economy stayed the same or improved slightly.
I then got the Smarty Sr. and run it on Level 1 and had even more power and lower EGTs by approx 100 to 150F (1150F max is the most I have seen with the Smarty even when towing) Economy has slightly improved by approx 0. 5mpg
No smoke what so ever. No issues with rough idle, ticking, etc.
I can go up any grade here in NW Oregon w/the 5er without having my foot buried to the floor.
When I unhook the 5er and drive the truck bobtail, I have a grin from ear to ear when pulling any kind of grade. The torque is just unbelievable.
I went with the Smarty Sr because I wasn't sure if the Jr would work with the aftermarket injectors, but I was being too conservative. I know someone that runs the Jr with 120hp KAX injectors and LOVES his truck.
I think 80 to 90hp injectors is the max you can run with the stock turbo because my friend with the 120hp injectors was above 1350F with his EGTs but the Jr dropped him back into the safe zone, he saw approx 200F reduction with the Jr on Tow setting.