unless you're particularly tied to a specific brand...you can pick up the foam attachment from home depot for about $20. If you don't like it, you can return it. I use it with my electric pressure washer.
http://www.homedepot.com/h_d1/N-5yc1...1#.UKl8xeOe-Gk
Pretty much get the same result... just make sure you use the a foam-heavy soap.
