If you have fit theses taps into a gravity fed system then you have made a big mistake and there is only one thing you can do to increase the flow rate, and that would be to install a twin impeller pump. If it is a mains fed hot and cold then you should not have any problems unless it is installed wrong and not been flushed out correctly and partiually blocked pipework or throat. Also if it is mains fed i hope you have provided adequate backflow prevention and elimanated cross-contanimation problems with you fresh drinking water ?