1 12 is all you ever need if it's done right, one 10 in smaller cars. my single 12 would put out enough bass to over power my highs (about 1200 watts pushing rainbow audios) and i couldn't take it in the car that loud.

i currently have 3 8's. that's only bc they were free bees and a buddy really wanted my old set up. once i have time i'll rebuild the box and have a sleeper 2.0 built in the trunk, and it also puts out more bass than i ever need.

remember less is more