I think they were 4" but am not a 100% sure (2 yrs ago). I used a set of polks from crutchfield for about $80. Sound better but not great, hard to get any bass out of something that small. I did not need to remove the roof to swap them out. The factory speakers use nuts & screws which will come loose if you keep pressure outwards as you loosen the screws(which you can collect with a magnet when done) the new speakers will come with clips and screws for install. Shouldn't take take long to do, good luck.