Suggest override to 5th gear, and run the speed that keeps you between 1800-1900 rpm. Do not use CC. If you want to use D, we have TCM custom tuning that will prevent 6th gear lugging, and 5-6-5 hunting while in CC.
These parameters should help the efficiency at higher altitudes particularly.
get me into hot water with State Emissions Control?
If you have an emission test to pass, you should leave it alone. If not, you have the (illegal) option of changing your exhaust and using a decent custom tune to circumvent the electronic consequences of the hardware change. Message me if you would like more information.
Re-useable filters have charted performance values that are no longer valid after the first day of its installed life. It can never be cleaned to obtain the same performance as when new, one of the many factoids these manufacturers will not tell you. Often, it needs to be cleaned when the oem counterpart would be at only 10% of its useful life. There is PLENTY of factual data to back up all the "forum" anecdotal chatter. Time to unsubscribe to this, yet another pissing match around one of the biggest DIY cons in placebo psychology.
Not really answering the original question, but re-useable filters, as a rule, are mostly for people with too much time on their hands. Factory elements will often go for 5 times the interval with the same resistance that builds up so quickly with a reuseable. That is because it has 5 times the filtration area. In one comparison that I did, the factory duramax element had 20x the fiultration area of the KN counterpart. It also had a superior filtration efficiency for the entire duration. I would likely never find a case for owning one.
I don't think they will even look at your obd port. AZ is an opacity test only for your truck, I believe. Have never seen them plug in for codes on diesels. They will also check for required equipment, CAT, EGR, DPF, etc.