10k ft elevation is about the only way I see to do it. Injectors have a horsepower ceiling not a pressure ceiling (as in there is only enough fuel to support x amount of horsepower) Barometric pressure at sealevel is 14.7lbs, pressure at 10k feet is 10.1 lbs all other things being held equal so you instantly pick up 3.6 lbs of boost just to equal the horsepower you made at sealevel. You can also turn up the fuel rail pressure to make the injector act larger than it actually is.
If they are running at altitude with fuel pressure cranked up it's possible, but they're pushing it. Dare I ask who you talked to?
