I replaced the stock speakers in my car. One new speaker weighs more than all four combined. Having said that, the stockers sound better than they should for how cheap they really are. The magnet is maybe the diameter of a nickel and 3/4" long. As for the HU, if you get into the hidden menu, (do a search, lots of discussion in the AV section), and turn off the EQ and Loudness, that will improve the sound some. It's free and takes a couple of minutes. After that, it starts to cost you. How much depends on what you want. I don't know if those settings are in the NAV unit or not, but we don't know what you're starting with.