Nothing wrong with a box thats tuned to 55hz, as long as its tuned with a flat response. Really I don't like to knock a box until its properly metered, by smaart or even term.
Are you building a box so you can do comps or you just want to be loud?
The size of the box has nothing to do with it bottoming out.
Haven't you heard my car? Tuned to 40hz, sounds great to untrained ear but missing out on 60hz to 125hz sucks. Thinking that a 6.5" or a 6x9" will produce that range efficiently without allot of work is madding.
Just think how shity this song would be with out 60 to 125hz
http://www.youtube.com/watch?v=auDv6cf2PBM.
And I hope Ryan corrects me on this but for some reason building a box that fires into a trunk should be NO bigger then half the air space in the trunk, because having your subs firing into the trunk turns the trunk into a 6th order bandpass.