[chevy72blu]

2" is far more than neccesary to down fire them. 1/2"-3/4" is plenty.

I dont really agree with the above posters. Downfiring seems to provide a better all around low end sound in tight areas whereas upfiring them makes the stage seem "punchy". Of course, every system is different and things such as box construction play a huge factor. Try both and go with what you like better.