I bought a pressure washer used from a shut down cement cleaning company for $125. It runs fine and I've used it to clean/stain my wood deck. Whats weird is that it has a 13 HP Honda engine on it. All the ones I've rented before only had 8 or 5 hp engines on them yet they all have said that the PSI was 3700 at about 3.0 - 3.5 gallons per minute. I can guess that the 13 hp engine is sure to top the gallons per minute and psi, but the pump has stamped on it 3.5 gps @3700psi. I quess my question is why even the 5 and 8 hp pressure washers say the same.