the big metal box...
limitations? stick boost in and itll blow to peices....
its the shape it is so the trumpets on each of the throttle bodys angle down, giving a long intake trapt for each cylinder (as long as possible without going to the extent of the 2zz). Giving more low down torque.
the factory 4-2-1 headers do this too, toyota didnt like the fact that they had no low down, so tryed to give them some. Honda didnt care, thus why a civic has NO low down
.