i dont agree with the above post as he wrote it
this is how it reads on the hurst instructions
press down on pedal ,
press line lock button and hold
release pedal (not line lock),
if needed you can press pedal again for more pressure as fluid will flow past the lock solenoid
so press pedal again while still holding the lock button
if your trying to do a burnout release pedal and your fronts will still have more hold then they did before and your backs shouls be free to spin
if you're at the line where you need more hold
press pedal
hold line lock
press pedal again and hold pedal hard
release line lock (keep foot on brake )
you should have significantly more hold than you did before to both the fronts and the rear brakes to build boost on
and by stock hydroboost i assume you mean powermaster as your sig lists an 87
but you really should look int the possibility of a weak master cylinder/ accummulator or weak rubber hoses or air in the lines
my 87 with powermaster has no problems just depressing pedal and holding line lock (lock solenoid after prop) , my 86 has vac and lock on fender before prop and sometimes requires another apply of the peday to get a good bite , have a tbrake for the at the line so no problem holding there
