Tires aside (or with stickier tires), braking distance will be greatly reduced by better pads. Also, its a lot easier to get to threshold braking with better pads even on the stock tires. So yeah, like Chris said, if you are really going for ultimate performance you need to swap tires too
Will HP+ Make a huge difference in your non ABS braking....I think so absolutely... it will change the feel of your car. You dont really know how hard you can brake on the stock tires until you get better pads....