well you admit that SS lines will not expand like rubber hoses. so if the rubber would expand, where does that force come from? and when that expansion is taken away, where does that force come out? the next weakest point in the system. if the firwall isn't very sturdy, it will give.
say you hold up a shock absorber to your car door. you push on it and what happens? the shock contracts and absorbs the force and the door is cool. do the same thing with a metal rod and push and dent your door. ok, i just made up this scenario, but do you see where i'm going with it?
i have seen a video of a guy's honda where someone was pumping the brakes hard and you could see the MC move 1/4" - 1/2" or so. i was pretty amazed. and i did concede that the lil japanese cars are less solid. oh, and the term "1337" is a computer geek thing, not a ricer thing.
ok, I don't want to jack up this guy's thread anymore, back to real info.