Must i flash to upload acoustics?

Must i flash my w550i fully just to upload acoustics? I am asking this because i have heard of people doing this without flashing and their phone has stopped working is this true or not?

I havn't flashed in a long time, thanks.

I can just use FSX through XS 2.2 can i?
2.2 Works best with w550 i heard.

you don't need to flash to upload custpack, just use the FSX

help me with my w910i...recently i flash it and accidently erased the fonts ttf files...what should i do?

make a full flash and your phone will be alright