errr what? i'm installing a pair of sealed xxls, and i have over 3/4 of my boot space still remaining, so clearly this has got nothing to do with creating me trying as much bass as possible ? I don't know of, nor have i ever set up anything where the sub is crossed over above 100hz, if your mids can't do 100hz cleanly then there's something wrong, my factory speakers will do it and they are junk....Nic on the other hand well he can't hear his speakers lol or himself think, but i admire the effort his gone to, yes even though his boot looks like a dogs breakfast.
Because you work in a car audio shop (presumaby?) therefore you think you know better than an enthusiast because you sell equipment.