You are missing a key point.
Pressure is related to flow.
That is why my [email protected]
pressure washer puts out 1600psi with the delicate nozzle that flows around 3gpm.
You need a surface washer that will flow enough.
and the pressure will take care of itself.
That being said having a commercial pressure washer you probably need a commercial surface washer.
something like thishttp://www.homedepot.com/p/RIDGID-Profes...31018/205581981
would probably work.. it has bigger jets on it and 18" so its made to flow more water.. than most.