Help ! Stilt BIOS for Sapphire R9 280, 280X Elpida

Hello,

Can someone helpe me please with a Stilt modded BIOS for Sapphire R9 280 Dual-X OC with Elpida memory, Sapphire R9 280x Dual-X OC with Elpida memory , Sapphire R9 280x Dual-x OC with Hynix memory?
I would try to mod it myself but i don't know how to identify the memory frequency steps. I know all cards have some VRAM frequency stages , for example 200 MHz, 400, MHz, 800 MHz , 1000 MHz, 1250 MHz, 1500 MHz. I don't know after which values should is search in Hex Workshop ( hex editor).