what van do you have, as you dont want to over load it, that is why a lot use 250 lit and some transits have 1000 lit, i only got a 125 lit tank (for £40 more could of got 250 tank) as wasnt sure if i wanted to go wfp, a di, battery, all pipes hoses reels etc, i just asked for the cheapest stuff they did, manily the own brand stuff, there is not much difference between them becareful as a lot will try and sell u expensive stuff, there is a window cleaner near me who has spent 16000 this year on a system and a 05 transit van
it worked out cheaper for me to buy it all seperate rather than in a ready built pack
systems are all the same, the only difference is if you use a ro or just a di what is the tds of ur tap water