Me an my mate have just got his frst on the road,but we'r having trouble curing the spongy brake pedal problem,the cars fitted with front st150 discs an calipers and st170 rear discs an pads, its still got its origional servo an master cylinder but we also added ka bias valves just befor the rear flexes along with the origionals in the bay as we wasn't sure if the rears would be to powerful ? It's been bled 4 times with an easy bleed kit an twice by manual bleeding,the pedal has quite a bit of travel an feels spongy but the brakes are working would having the ka bias valves cause an air lock ? Or should we remove either pair of bias valves?Any help greatly apritiated

Chris