what do you mean by makes a difference and makes you say WOW?
If you are expecting the foam cannon to be a miracle car wash product that you just spray on and rinse off and your vehicle is spotless, you are going into this with the wrong perception. You still have to go over the whole truck with a good microfiber wash mitt or sponge. I'm not saying this is specifically your expectations of a foam cannon. More just wanted to get the info here for someone that doesn't know.
Agreed.
The foam gun/cannon is "another tool in the bucket" IMHO.
I use it once as a pre-wash...after pressure washing the whole vehicle, I will foam one side of the vehicle and let the foam dwell/slide off the car.
Then I will use it as Im washing...aim foam between the wash media (my favorite is the Meguiars microfiber mitt) and the panel while you are "washing" the panel. Provides lubricity to make sure you arent going to mar the paint along with helping the dirt come off. I will do the upper 2/3-3/4 of each panel first, since the real dirt resides on the lower.
Finish one whole side by doing one panel at a time, then go back and do the bottom 1/4 (rocker panels, lower doors, etc) with a wash mitt dedicated for lower panels.
Then rinse the whole side and continue same process for hood+front bumper, other side of vehicle, then tailgate/trunk+rear bumper.
