Im currently running CT Mod 3.80 I guess wanna do the sd ?
Here is what I have done.
Make a cwm backup and save the entire sd card to the pc.
Turn off phone and eject card and put in new card.
Use power button and vol up and camera button all at once and that will boot phone into cwm.
Partition card at any sizes and when done boot up phone.
When booted up go to settings/ct rom/then sd parter.
Slide the fat to the left and on the next line below set at 1000(+or-50) it is hard to get to an exact number, make ext4.
The next one under that make 500(+or-50) ext4 (or swap if running data mode and swap only)
The next under that make 500(+or-50) swap.(Optional if want ssm with swap or might want it later)
Then click start process.
When done copy sd card from pc to new card and restore your backup and will have what you had before with a better card.
If want ssm and swap you need to select them in settings and have to redo everything like apps and home setup.
Don't know what you were running before and want to run now but is the easiest way to, If you mess up and need the phone till you have time to fix just power off put in old card and reboot into cwm and restore your backup and will be the way it is now before starting any of this.
Hope this helps!
