Ready for something different.... When I fitted my high specs they were spongy as hell and my dad taught me a trick which may/may not work but it worked for me. Mine were spongy after replacement and full fluid replacement so what he told me to do was go home and pump the brake pedal so it was as hard as possible, then I had to wedge it down as hard as possible which compresses the fluid removing any air in the fluid you cannot bleed. I did this and wedged it hard with a stick between the pedal and seat. Next morning the stick was sat on the seat and the pedal was perfect Have a go, he's been in the business 35 years and it's an old trick apparently, but it worked a treat