JoJoDFG said:
As you can see I don't know anything about sound...Is there really room in the boot?
Basics on sound (very, very basic - don't be insulted if it's too basic):
To make sound, you have to move air. The lower the note, the more air has to be moved. That's why woofers and subwoofers are large.
The dash speakers are 4" speakers, and they can't move much air, so you can get great highs and mid-range, but no bass to speak of. There's no way around that. If you get a good quality 4" speaker, it's perfectly easy to expand it later and go with larger speakers in the parcel shelf. You just get an amplifier with a built-in crossover and send only the high and mid-range sound to the front speakers, and send all the sound (accented toward the bass, if you want) to the back speakers. Since you're not calling yourself an audiophile, you won't have to worry about the picky details like having the response matched between front and rear, or phase differences caused by different distances between speakers, or any of that crap. It's all pretty much useless fluff in a convertible, anyway.
I'd get an Infiniti or comparable 4" 2 way speaker. That means it has a 4" cone to produce the mid-range sound, and a smaller tweeter to produce the highs. You can later, if you want, add an amplifier and 8" two or three way speaker in the back to produce the low end.
It would be useless to put them in the trunk, because there's too much between the trunk and your ears.