Old Cummins Pyrometer and Jake Brake Questions

The old Nh/Nt’s love high rpm. Like has been stated. 1750-2100. They breath better at that rpm and 900-950 pyro will be normal. If jaking down below 1600 you need to drop a gear or half and get rpms back up. Being mechanical u cannot let it lug down. Jakes will stall out the engine easy once it gets down below the torque band and leave you without a paddle pretty quick.