Hi Charles, ok, IMHO, to me it sounds like 1) defective pressure valve and 2) unmatched or defective master brake system. IMHO, your "kit supplier" should be able to supply you with the "Specific Hydraulic Specs" for the system as a whole and the individual brake components. If they can't or won't, run don't walk away because they have done no engineering on a critical safety system...merely going by general swag component comparison...Ö SWAG is ok for those working in their backyards (with trial & error testing), but for a company selling and making $'s, this is, well, you know.....there is a legal word for it.
I would go back to what has been successfully used for 30+ years prior...Ö go purchase a 1974 V8 Ford Maverick master brake cylinder....they come in power, non-power, drum/drum and disc/drum versions (and if you do a little R&D, there are actually successful applications using this with disc/disc). You will now have a MBC that is specifically designed for the size, weight, power, braking systems of that car..... my swag is you will at least have a system that is functioning..... will the hydraulic volume be enough? Only your component mfg will know....if they won't help, get rid of their components as well, replacing with oem spec components and upgraded brake linings (CE of .49 or +)..... this should put you in about the same performance range as most of these aftermarket systems...Ö. remember, the aftermarket systems cannot (regardless of the PR
) give you race car like braking on the street...for two reasons....1) the system will override the cars ability to stop....meaning it's functioning at a far greater efficiency than the tires, suspension, etc. is designed to function at...so guess what...actual stopping capability is no greater in most cases than a properly setup system and 2) If they really did give you a race car type capability...you are now at risk of stopping faster than most anyone else...meaning you are now at risk and so are others on the road.....there is a "performance range" that is considered "acceptable"...and yes, a 911 can out stop a Kia but when you look carefully at the full spectrum, if the drivers are paying attention, each has the ability of stopping before hitting each other (too severely).