Bit of an update:
Just rolled over 6,000 trouble free miles since purchase, time for an oil change. Got 12 quarts of Mobil1 full synthetic for $75, a wix oil filter, a wix air filter and a can of seafoam. I haven't changed the oil yet, but I tried an experiment, before replacing the air filter, I ran the truck though a 0-60 run without a filter, just to see what difference it made.
Quite a bit it turns out. Given the intense maintenance regime the previous owner kept to, it's a safe bet the air filter that was in there was at least 8 years old, and even though I blasted it with some compressed air, the little vacuum indicator would always be maxed out, even if I never went to full boost since the last time I checked it. Also, when I planted the go pedal, the boost would always taper off near redline. Without a filter, it held at 20 psi all the way to 3200 rpm. With a new air filter, it did the same thing, and the truck is more responsive and feels more powerful all around.
One thing I did find out, when running without a filter, is that I can hear the turbo much better with an open intake, so a quality intake is on the list of upgrades. Because turbo noises are cool
