I've bought some 3/4"x 15mm flexible hoses with an isolating valve built in to plumb in a bath and I've noticed the internal bore particularly through the valve part is very small approx 6mm. My hot and cold water pressure is not very good so I'm concerned that this reduction in bore will effect the flow further should I be concerned. I would like to use flexi's as once the baths in it will be impossible to get access to tighten up the connections so are there any large bore flexis available and would I be better off using a separate isolating valve rather than a built in one.