You're not making more power because of the gear ratio, you're just making better use of what is there. The HP ratings are the same. A numerically higher ratio puts the engine in its powerband sooner because the engine has to turn faster at the same road speed compared to a numerically lower ratio. Do you see the auto manufacturers changing the motor's HP rating depending on the rear axle ratio? Nope, an S-10 4x4 with a 4.3 had 190 HP and 260 Lb-Ft of torque, didn't matter the axle ratio. One just felt peppier than another becuase it was in the power band quicker and was making use of the power it has.
Gear ratios are also a way to offset tire size changes. Example, my
2000 S-10 ZR2 feels like accelerates about the same as my old 94 Jimmy did. The ZR2 uses a 31x10.5 tire, the Jimmy had 235/75.15's on it. The Jimmy had 3.42's, the ZR2 has 3.73's, the tire size change and gear ratio change put the engine right about the same place at cruising speed. If the ZR2 had 3.42's in it, the engine would struggle because it wouldn't be in its powerband, so the 3.73's in this case might actually HELP with MPG.