The 60 Inch Subwoofer (60 tuumaa = 152.4 cm... joo...)

The woofer was designed with the capability to produce SPL levels of 188 dB, which are entirely possible, given an appropriately built vehicle. It is simply a matter of displacement and containment.

It hasn't seen the light of the car audio industry since 1998 for several reasons. First is money... It isn't cheap to haul it around, and unless it would produce some significant return on investment... You get the idea. Basically, it would be a very high price to pay for some entertainment value and bragging rights.

Full story from here