[TboneS54]

I went with a westinghouse pressure washer because the GPM was the highest of any cheap washer (1.76 - most are 1-1.2). I wouldn't worry about pressure, but I would reduce the orifice size (to 1.1 - usually they come with 1.25) for the foam cannon that you use. That's where you do want more pressure to get good foam. For rinsing, you want higher flow, not pressure.

For the 25/40 spray tips, I went with orifice 2.5 because it matched with my specs (1.76 gpm, 2100psi) based on hydro mtm's calculator website. But I'm thinking I will try 3.0 to reduce pressure further.

However, I don't mind slightly lower flow when rinsing the car off as it should increase the effectiveness and extend the life of my DI resin :P