There probably won’t be a decrease in power, as it was likely an aftertreatment issue (sizing, durability, cost cutting) that made them decide to use a defeat device. Cummins would retrofit every cheating engine with a brand new aftertreatment system at great cost rather than reduce the power of their engines. The brand damage of reducing power would far outweigh any repair and warranty costs.
Hi friend, what are the immigration policies for your country? Asking for myself