well, since this seems to be a big deal, i'll put in my opinion, how i think it should go is slow zombies, like the building walking speed permantly, however, give the numbers a huge buff (pretty much as many as the system will allow at one time in a given area) and then make it so they're agro range is alot larger, that way you can sprint in and loot, or still take a semi safe approach (by increase agro range, i'm thinking keep the sound while walking roughly the same, increase some bullet sound, then sight range and such get a buff, along with a small radius that they will always detect you in. also, health buffs, give them the same ammount as 10k blood, but make headshots do 15X damage or something