so I have this strat and I want to change the bridge pickup so that it can handle down tunning a little better and have a humbucker sound. I play ostly brutal ass death metal. Please some suggestions. P.S no active Pups

DiMarzio Super Distortion S or DiMarzio Tone Zone S. They're DiMarzio's highest output single coils, but the output still falls a bit short of humbucker output. You might want to consider replacing the middle pickup too and using the pickup selector to select both the middle and bridge at the same time. That'll give you more output.