Installed mine on an 06 Legacy GT with a 17/16ths Master Cylinder from a 06 WRX
My mechanic had never seen a master cylinder brace before and had to question how it was installed. I showed him the graphic shown above and that was all he needed. The only reason I am giving it 4 stars is I don't know how much of the improvement I can attribute to the brace alone. I also replaced my calipers, rotors and pads with the following kit: https://www.fastwrx.com/products/subaru-four-pot-2-pot-full-brake-upgrade-2005-2009-legacy-gt All items work together on stock rims. The brace butts up firmly against the 17/16ths WRX master cylinder. There is definitely less pedal travel before I get to firmness. On my way home after picking up my car I hammered the brakes pretty hard. I could barely get them to lock up but that is due to the ABS. They were definitely far more firm and responsive with none of the squishiness that I was trying to resolve. This part was a drop in the bucket for the price of the rest of my parts and I wouldn't do the upgrade again without it.