With all the customization that Android offers, coupled with the amount of content available these days in terms of Custom Roms, Kernels, modems, mods, themes, etc. it can be very easy to flash an incorrect file inadvertently, and end up with an errrm.. expensive paperweight. How often have you read posts in forums discussing which modem is better with which ROM, and which kernel offers the best performance??
XDA member Peaster111 has taken the effort of creating a one-stop thread for all the modems compatible with the AT&T Galaxy S2 ─ All Roms, custom or stock, for the AT&T SGS II contain one of these modems.
Please note that this is specific to the AT&T branded SGS2, and is not meant for use with other devices. The modems are categorized into Stock & MIUI/CM7 sections making it easier for you to pick the right ones. You can download the zip file of your choice and flash it through CWM.
For Samsung ROMs
For CM7/MIUI ROMs
Currently the list just features the modems currently available for this device, and its not too many, but Peaster111 intends to keep updating it as and when more modems are made available. You can follow the thread here.
Enjoy and do let us know your thoughts in comments below.