My brother recently purchased a Civic Si 2006 up here in Canada. He wants to upgrade the speakers but is unsure what sizes come stock in his car. Anyone have any clues?
I have a '05 Accord Hybrid and also am looking to do the same, I have the same question!
Thanks.

Unless Honda's changed something in the last year, both front sets of speakers for both cars should be 6 1/2" speakers.

The rear speakers? are they 6x9 or 6.5"?

Sorry...forgot the rears. Usually, they're 6.5, though I've seen the occasional 6x9 in the Accords.