CP3 in Ram verses CP4 in Ford and GM

As for why the ISB 6.7 motor still uses the CP3? I'm betting it's emissions credits. Cummins has always been good about gaining emissions credits. This is largely why their 5.9 motor never needed to use an EGR system (except in California) while the Duramax and Powerstroke motors did. I'm sure they're now using the credits they gained with the 2007-2010 ISB motors as the ISB motors made in that time period exceeded emissions requirements and allowed them to build credits. I'm pretty sure that the reason Ford and Chevy are both using the CP4 is because of that extra 3,000 psi of injection pressure to get finer atomization and reduce particulate emissions and help with other exhaust strategies that I'm probably not aware of. But be assured, once they run out of emissions credits, they will eventually move up to a higher injection pressure unit. With the 5.0 adopting the Bosch CP4, I can guess that the ISB may eventually see the same pump. Otherwise, Maybe they'll use their XPI pump on the 6.7 since it has nearly the same bones as the 8.9 ISL motor. That's what I'd like to see, as we've never really had issues with the XPI injection pumps we have on our municipal fleet(s).