What does the speaker size refer to + dimensions of door card insets (uk wrx)?
 

If a speaker is 16cm, what does the 16cm refer to? Is it the mounting hole, or the external diameter of the speaker?

If it's not the mounting hole, is the mounting hole size standardized, and if so is there a way to calculate it or is there a table to look it up?

Also, does anyone have the dimensions of a door card inset needed to fit different speakers to an 03 wrx?

I would have a look meself, but I'm on holiday at my parents (who have a load of MDF :)) and the car's at home, so thought i'd get the bits and bobs done here so I can install door speakers quickly when I get back home

16cm is overall diameter.

mounting hole and depth differ from speaker to speaker, as the basket chassis is differnent to all. some have deep baskets that cut in at sharp angles straight away, others may have a shallow basket that stays wide til the end.... check manufacturer specs before buying.

not sure about my03, but in my late classic, i got a set of Bostons fitted, which have a mounting depth of around 64mil. i made myself spacers from 12mil mdf and extra depth with some sound deadening....

hope this helps