[GUIDE] How to / Pro's & Con's Flashing over stock. topic

I realize, there are a few different (small) threads that described, or contained information about flashing over stock. Even a thread of my own (Horrible title, used a rom's name in the title, effectively singled out everyone else). I've browsed these thread and added all info here.

Requirements:
Root & Safestrap 3.75 (*1)

Basic how to:

1. Reboot to Recovery/SafeStrap


2. Select stock partition


3. Make backup of stock partitions, ALL partitions.


4. Using advanced wipe: wipe /data (*2), /cache and /system


5. Install custom rom/gapps


6. Reboot and enjoy!

Pros:

• Rom appears to load/run faster (*3)


• If you don't use stock, you can now re-use this wasted space (*4) about 6gb's

Cons:

• (XT912/KEXEC roms) If custom rom is flashed to stock - DO NOT UNINSTALL SAFESTRAP!! (*5) Must preform "Reversal"


• Doing a factory restore will wipe stock slot (using batmans utility), while your slots (1-4) will stay intact because each slot is actually a file stored on the internal SD card, partition.


• Can't use BP_Tools for flashing. Boots into safestrap instead. Must preform "Reversal"

1. 3.65, 3.73 had some bugs/quirks that are NOT present in 3.75. In order to follow everything here, and NOT have to deal with errors other users had reported in the other threads, please update to 3.75 before following this guide. For example, users reported : Wiping stock, removed safestrap, causing blackscreen. Or, when wiping by checking all check boxes, safestrap would quit with error, and NOT wipe the remaining checked partitions. If such user wasn't aware of this, they would complain their rom wouldn't boot/crashes without knowing the cause.
   


2. Some/many applications will refuse to update if they were installed on the stock slot before installing the custom rom without wiping data.
   


3. Personal observation, no hard data. I remember at the time, when I first did this, there was a SIGNIFICANT increase in boot speed, stock vs slot
   


4. Slot 1-4 uses internal SD-card space. Stock slot uses partitions. Wiping the stock slot in hopes of making more room for slots 1-4 will not work. The only point of this is to re-use the stock partitions, so you don't have to waste space by creating a new slot.
   


5. Custom roms on XT912 use KEXEC to boot those roms, if you remove SafeStrap, your phone no longer can boot that custom rom, you will be stuck with a locked down/rootless abd shell and a black screen.
   

Reversal:
Backup custom rom / stock slot.
Restore stock rom / stock slot.
Boot stock, open safestrap, uninstall safestrap.
OR
Backup custom rom / stock slot.
Factory restore using Droid Razr Utility (Data wipe option)
You WILL have to WIPE DATA. The stock rom will "forever boot / hang" when your data partition "dirty" from your custom rom aka "Dirty flashing"