I'm hard of hearing so take this with a grain of salt. It sounds identical to the numerous up-pipe exhaust leaks I've had on my 7.3 powerstoke Excursion. With the Cummins, it would have to be exhaust manifold to head or under the turbo. That would also explain your low boost, although "30 at least" doesn't tell me if you aren't seeing 50 psi. I don't know how much fuel you can force through your stock injectors, but if it were a lot, I suspect you would be seeing higher EGT's with the smarty, but your thermometer said it was 35 degrees of cold, dense air outside, so I don't know.