I use Greenworks 1700psi with Uber foam attachment and it works well for me. It comes with three different nozzles to change stream width I use the middle one (25%).
Pre-soak the area with the Waterless Wash. After leaving it in for few minutes and then the wash the area like you would any other area.
http://www.adamspolishes.com/t-Detailing_Video_Vol_8_Chapter_14_Removing_Bug_Guts.aspx