Hello,
I would like to know which acoustic is the best for W580i

Try Rakista Zapfed or Peter's v2.

http://forums.se-nse.net/index.php?showtopic=16379

http://forums.se-nse.net/index.php?showtopic=28265

try this acou this is designed for slider phone :

http://forums.se-nse.net/index.php?act=att...st&id=23400

you should try hyper t's hyperdrive 1. Incredible loud sound with no crack at all. I had beaten my friend's w810 with rakista massive bass which makes my phone (w580) King of SE.

But before that u must make the acoustics compatible with ur phone (slider):

Copy every farfield and add "_closed" after "farfield" to the copies.
Example: farfield_call -> farfield_closed_call

Do the same for handset_0_call -> handset_0_closed_call

hope this will help slider user when choosing acoustics