I have noticed how identical machines with the gx270 and cat pumps are rated way lower than their AAA counterparts. For example, this tool has a gx270 and has a seemingly better cat pump makes 3,200 less cleaning units than this other tool which has the exact same gx270. It also seems like you would need almost 10 horsepower to make 4000 psi @ 3.5 gpm, like this tool says it does with an 8.5 hp Honda. Is Simpson lying about their numbers? Or do the AAA pumps actually make more pressure but just not last as long? I don't care that much about psi either, but the NorthStar unit also has a lower gpm. I could just go with something with the gx390, but it is a much larger engine, and it would be a lot heavier, louder, and harder to carry around and move into a car. I know I sound like a repetitive idiot, but this whole thing is really confusing. Thanks in advance to anyone that can answer my dumb question.