First off efficiency ratings, and capacity ratings are for SEA LEVEL. The air in Denver is much thinner to begin with. Even blower performance charts are somewhat inaccurate because they too are based on the air density at sea level. Assuming 5,000 - 6,000 feet. In some areas (per the amana i/o) the gas companies in high altitudes, may artificially derate the gas to compensate.
I'm more than a little concerned with "plug and play", Depending on the mfg, you likley need to have had an oriface change along with an adjustment for manifold pressure. The ECM motor software is programmed for sea level density.
I can safely say, that if your furnace produces water in low fire, its firing at over about 88% minimum.
you still need to clock the meter, know your gas value, and know your vent temps at a minimum.