Alternative detergent injection or x-jet alternative

Hi,

Does anyone know of an aletrnative detergent injection system i.e. alternative to the ones that are 'built into' the pressure washers. I want to be able to control the mix of chemical and water better. Right now, I can spray on an unknown mix percentage with the tube that came on the petrol washer. Even that mix percentage varies depending on the length of HP hose I have attached.

The x-Jet nozzles appear to be a great idea - you can choose the mix you want, you don't need to worry about the length of HP hose, and I assume that Hypo isn't good for HP hose (anyone know)? so that isn't a worry either.

The problem with x-Jet is that they are expensive and have to be bought from the USA.

So, any alternative detergent delivery systems out there for pressure washers?

Not when using hypo really as the xjet fits onto the end of a lance/gun therefore you don't kill your pw pump hoses, fittings and lance as hypo will destroy most things at a cost.