BattlEye only checks for certain bytes in PCI config space:
As long as your FW doesn't have those bytes in the PCI config space, you won't be detected. So, get a good FW. Also, writing to memory is risky regardless of whether you are using DMA or not. This is "detection" type of ban.
There is another type of ban called "manual ban". In this case, BE AC or BSG doesn't or cannot detect anything but they ban you because you are way too obvious with your cheats (e.g. aimlock to PMCs head ).