re: What psi pressure washer do I need?

I use a Karcher 3k psi @ 2.5 gpm (Honda powered) power washer (10 yrs old). I have > 2500 ft2 of driveway, sidewalks, and patio to clean (also brick, a picnic table, a boat, tractors, etc.). You can't clean pavement with the spray heads that come with the pressure washer. No Way. At best it will look like zebra stripes. I use a Karcher 12" round pavement cleaner attachment that works very well. Mine is all metal and was 3 or 4 hundred bucks. It has a twirling wand inside with 2 nozzles. You can buy cheaper plastic ones for under $100 (Home Depot, Lowes, etc). They won't last as long. My 2 cents.