It all depends on how good your speakers are. A pair of 10's can completely crush a pair of 12's if they are good 10's. For example, MTX Thunder 8000 10's vs MTX Thunder 4000 12's. The 12's simply aren't going to hold against such good speakers. There are too many factors to consider to just stereotype 10's and 12's as being boomy of accurate. This is a really good install, one of the best I've seen in a mustang due to the extremely small trunk.