you do not find the pickup for death metal..
death metal and metal in general has to come from within you! and then you let that voice from inside to speak through your fingers and guitar!
if you have a high gain amp or a heavy distortion pedal you can do death metal with a vintage fender!
but that's straying off topic, we're after good tone, not a matchbox full of bumble bees right?
my $0.02 first and foremost, for downtuning you need a tight pickup to retain the punch when playing in dropA and not having it sound like soggy spagetty.
my guess, from the BKP's is the warpig. there's a clip there with the warpig that is tuned in .. E, an octave lover than standard :twisted:
i gotta spend more time in the players room and tune my ears to BKP's but in the meantime, you got lots of other people giving good advice here =)