Based on what I've seen with before and after results on this setup at high altitude, and CF dyno numbers I suspect my truck that ran 13,7 stock, and 13.4 with the turbo upgrade would probably be about 13.1 at close to sea level, and JD's turd would be a mid 12.7 to low 12.8.
Take BFT's truck for example. He's still on stock fuel, crew cab, 37's, and high power compounds. his truck still only ran a 12.7 in Arizona. maybe could've pulled a 12.5 on stock tires, and he's got way more air than JD who ran a 12.98 the same day with smaller tires and stock turbo. Robert's setup runs super low temps, pulls like a freight train, and does it day in, and day out almost completely smoke free. He could have way more power on tap with as much air as he has available, if he added fuel, but for what he does it's perfect. Maximum efficiency is the key on Roberto's setup.
The relatively big power gains we're seeing here in Denver (70+ rwhp, and 100+ tq) wouldn't be quite as impressive at lower elevation. I suspect you'd see somewhere in the neighborhood of 50+ hp and 80+ tq to the ground because there's only x amount of fuel to burn, and denser air at low elevation would be like those of us in the mile high club, er, city to be running a small amount of nitrous all the time to make things equal. Just the same, once nitrous is added to a power equasion, CF goes completely out the window aside from pre-nitrous spool up time, so a 1000 hp nitrous run on a corrected dyno at high elevation is much less impressive than a 1000 hp nitrous run on a corrected dyno at low elevation. take away the correction factor, and that 1000 hp run at high altitude suddenly becomes 875ish where the one at low elevation would still be hovering around 950ish uncorrected. There are tons of other things that come into play to establish correction factor like humidity, air temp, etc, so I obviously can't be exact in those figures, but the point is still valid.