So I'm sure you have seen the yahoo home page, where the Canadians came up with that speed bump pavement Patty?
I started SCUBA diving back in the late 1970's and back then I heard stories of old guys converting old fire extinguishers into SCUBA tanks. So yes I'm sure it can be done, my question is why take the risk?? The max pressure a fire extinguisher can handle will be printed around the neck of the bottle by the DOT stamp, the pressure number will be in PSI, all bottles are different. Again I have to question why?? Scuba tanks are pretty cheap and very easy to buy in all different sizes. When I started diving all we had was steel 71.2 ft/3 tanks.
Skullcandy does have a lot of bass, so do some of the Altec Lansing ones. Personally, I use full-size studio headphones (Audio-Technica M50) so I can get real bass. And when you wear full size headphones outside, everyone thinks you're a dj.