Do we have 13 millimeters speakers in our cars? Why do I ask? I am able to buy those and I need to replace the speakers in my car.
The price is 12 dollars for both. Is that a good price?

http://bildez.lv/bildes/uvis/for_sale/1240937938.jpg

The speakers all have odd sizes... 13 cm (5 1/4") is too large, 10 cm (4") too small. But you could always modify the speaker pods to accept larger speakers. Several people have installed 13 cm and even 16 cm speakers in the enclosures.

Or you could remove the speaker enclosures completely and make a speaker board from MDF wood.

I used 5 1/4" speakers, smal dremmel job to make them fit, but no real problem.

the rears are where a lot of the customization comes to play. You can easily dremmel the kickpanel enclosures, but it won't be reversible. The rear speakers are actually a 3 speaker circuit setup, I've opted to nix the enclosure and make my own board like Revtor suggests. I believe the options to be near limitless with what you can do in terms of sound for our cars, there are brilliant write ups on RF. I'll be finished or almost finished with my setup this weekend, look forward to the thread :).

I did 6.5 in the kicker panel
Tweets in door
1 thing you shoud understand about speakers
if you are looking for good sound find a set of mids and tweets with the crossover
package.
If you mix and match it will not sound right then you will need a bunch of eq garb, and 1 might over power the other.
Can i get an AMEN!!!