You should be rooted and have custom recovery installed.
1) Keep it SD card and reboot to recovery.
2) Wipe data/cache and dalvik and then flash the ROM, incase you get a bootloop (which you won’t) then reboot in recovery wipe data/cache and dalvik TWICE then again reboot recovery from advanced menu and then install the ROM , Flash SuperSu and reboot.
3) Will work with any cwm recovery
4) Reboot and keep patience as first boot can take upto 15-20 minutes.
– ROM can’t take screenshot from “Volume UP or Down + Power Key” but hey Gravity Box is there!
– Mms App can’t Select sim while sending message so install Infinix Default Mms Apk
Also Download Dolby Here