Good flow rate low pressure taps

[tonyb61]

We have a gravity fed system in our bathroom, both hot and cold fed off the tanks in the loft. We wanted to put more modern taps in. We chose some Bristan single lever taps, designed for pressure down to 0.1bar but the flow rate is really poor. The old Ideal standard ones worked really well, with a good flow rate but these are not good. We need a monobloc basin tap, are there any good makes that achieve good flow rates from tank fed supplies ?

Thanks
Tony