The best selection of injectors has not only to do with the modifications of your truck. It is also a choice of personal preferences and the preferences of your tuner if you plan to get custom tuning for your truck. Also the main usage of your truck has a lot to do with the selection and if you have to stay emission legal.
For that reason, we have done emission testing in the state of Washington for the smaller Stages of our injectors. For the 5.9l Cummins the Stage 0.5 passed without tuning on stock trucks for the MY03 and MY4.5 truck. Stage 1s will already require a tune to pass the idle snap test.
With the 6.7l truck the Stage 1.5s passed the test with a stock tune and a stock truck (no deletes)
For street trucks and daily drivers our Stage 0.5 and Stage 1 injector are the most common used Stages. Stage 1s are designed to get the max out of a stock CP3 which is between 680-710WHP. Stage 0.5s use the same nozzle but have a shorter mechanical injection time which has benefits if you don´t want to use custom tuning especially when towing as it will get you lower EGT´s. (it is comparable to using earlier timing and shorter duration with the ECU) If you are looking for more horsepower than that, here an application guideline that should help selecting the right injector set: