[thstone]

I had a brake situation similar to the OP when I first bought my used Boxster - I'd slam on the brakes at about 50mph and it seemed like the car just didn't want to stop and the ABS wouldn't kick in. I also tried pad break-in runs with no improvement.

I also replaced the tires with Michelin PS2's. Whether PS2 or PS3, the tires should now be fine and giving you all of the grip needed to stop very well.

I decided to start at the obvious and work my way up so the first thing do to was to replace the rotors and pads (I went with Cquence drilled rotors and EBC Redstuff pads but any good rotor and pad would be fine for the street). I also installed the GT-3 brake ducts at the same time (cheap and easy). Didn't touch the fluid or ABS system.

Now I can stop on a dime and as another writer commented, I have to be careful about out-braking the car behind me on the street and worry about getting rear-ended. Also, now if I get on the brakes hard, I can get the ABS to engage and feel the judder.

If this hadn't addressed the issue, then a full brake fluid flush would have been next.

If pads, rotors, and fluid hadn't worked, I'd have taken the car in to a mechanic or dealer for evaluation and see what they recommended.