Do you guys have 6"s in the front? Aussie civics come with 6" fronts. Infact, almost every Aussie car does. Is that like a madly uncommon size in the US? Over here we have 4", 6", and 6"x9". Whats this 6.5" and 6"x8" and 5"x7" and the likes. I searched US ebay and found1 x 6" pair of xplod speakers for sale out of 4383 listings under car speakers.

 

Not sure about the 6's.

Most US people use 4x6, 6.5, and 6x9's here. Some older cars or smaller cars use the 6x8 and 5x7's. I am not sure if anyone even puts them as OE in cars anymore, in fact I have only seen 1 older vehicle that had the 5x7's in it.

They used to make some retrofitted 4x6's too, that had a 3" woofer and 1.5" tweeter mounted seperately. My old BMW had 4 4x6's in it, they sounded horrible.