This spring I installed a Greggs brake proportioning valve on the front brake system of my car. I have been adjusting it ever since and now have it set very well.
I used to get front tire squelling during very normal stops and lock-up sometimes in hard stops, not panic stops. Front tires are 235X60 Good Years.
I put it forward of the existing front brake T that carries the brake light switch, it bolts down to the frame. I did not want to make new lines because of a sealing issue on the left front caliper, I was able to find adapters to put everything together and keep the originals. I bought the adapters from Pegasus Racing in California, great folks and very helpful. My biggest problem was sizing all the fittings.
To put it all together you have to go from english metric to SAE sizes.
Anyway, it works great, the car feels so much better under hard braking conditions, front and rear brakes both seem to work better.
Under all braking conditions now the car feels much more solid and linear, no more sliding when stopping hard.
Cost for everything was about $80.00.
The best way to do it is to remove the front luggage compartment floor panel, naturally I did it the hard way without doing that but I have a lift.