Autobrite magifoam is what I was using, just ran out actually. dilution ratio is just the recommended, 1-2" in the bottom of a 1l bottle. I also got a smaller orifice for my snow foam gun.What foam are you using and what PIR are you at. The power of the washer should not hugely matter.
Bilthamber auto foam is regarded as one of the best out there and really good value for money
This was my foam (best I can get it, and I've tried! although it might be the foam cannon being crap) after about a minute
My washer is only 200l/h and 2.4mpa/24bar which compared to a 'real' pressure washer is pretty low. 130bar and double the flow rate for a proper one.