Hi. Funny I got my lance via a detailing world recommendation. I'll try different mixes. Works really well as you say.Funnily enough it's Bilt Hamber auto foam. Fantastic stuff with awesome cleaning power. Have you worked out the flow rate of your pressure washer so you get the concentration correct in the foam Lance bottle? Also, are you using a decent snow foam Lance? Both these things will make a good difference, I can link you to a good thread on detailing world if you like? I found I need 300ml foam to 600ml water in the bottle and my Nilfisk C120 likes that and it will cling well while I work around the rubber trim and other areas with a detailing brush and APC and I rinse after 3-5 mins.
Edited to add Bilt Hamber is definitely not the thickest foam on the market but it's probably the best pre cleaner you can have for this stage.