Cheapest ways to increase power

Been said...gears. We had a 170 slant we changed out to a 225 because this car couldn't get out of its own way until the next light, and the 225 was no help. Turned out the guy had 2.54 gears out if a Cordoba! Next time I saw him he got some 3.73 gears for that rear and he laid a strip of rubber to show it off.