My set up is mains in at tap pressure (55/75). What pump did you get - is it 240v? - and where does it go in the set up?
Do you bother with resin?
You could probably get away with a low pressure membrane (HF5) un-boosted at those pressures but I would call Doug first to be sure.
If you do go down the high pressure membrane route (HF4) then I use this booster:
https://www.anglianpumping.com/product/water-boosting-pumps/jet-dp-102m-230vAnd I have it before the prefilters.
I wanted to put it between prefilters and membrane (mostly to save any sediment running through it so it would last longer) but it would have meant lengthening hoses etc… and seeing as the RO came pre built, I couldn’t be bothered farting about.
I do use resin, I have a 25 litre vessel that probably needs changing once a year tops so it hardly breaks the bank so I figure, why not?
(We go through 650litres pretty much most days)