I've heard many good things about firmware C being of the best I know that we have the options to flash via the unbrick guide. but can anyone upload a flashable zip. i don't have a computer but I am rooted and able to flash it.
I don't think you'll get very good results with just the phone doing an unbricking.You'll need to know all the ins and outs of the firmware and the phones behavior just to stop all the processes that will occur when you first boot. you will need all the necessary apps to allow the phone to maintain The " C" versions integrity. I beleave it will require a pc and some skills achieved from intensive reading in these forums.
yeah you cant go back to c unless you "unbrick" but remember unbricking (flashing new firmware via kdz) will not delete your data or apps. my best advice to you is see if you can install the software on someone elses computer and downgrade that way.