It'd be nice to add some nice aftermarket symposer noise on turbocharged car without buying a whole new car. I'm talking here about the tube that runs from the intake box into the cabin (not the one that runs through the speakers).
Now I know what you're going to say, why not just get an aftermarket intake and be done with it? Well, some people want some nice acceleration noise without all the extra air noises.
Let me explain, I have an aftermarket intake on my turbocharged car and while it sounds great most of the time (whoosh...psssh, if you catch my drift), it can be kind of annoying in my daily commute when I'm driving along and just hearing the sound like air is being let out of tires.
A sound symposer that you could add to a stock (or afttermarket) airbox would be the best of both worlds IMHO. Sweet sweet induction noise when you want it, with no "whooshy" noises when you don't.