Re: Metal pickups
You want to add that bass later in the signal generally (EDIT: this is assuming that tightness is a goal. For early '90s kinds of downtuned death metal, where you need it to be a bit looser to get the right feel, none of this applies). Instead of going with a more bassy pickup, you'll be better off either turning down attack on that PD or turning bass up on your amp. The reason more bass can make your tone loose has nothing to do with the amount of bass frequencies on their own (bass amps produce more low frequencies than a guitar amp ever will and stay tighter in general...), but rather how bass interacts with your various gain stages. If you add the bass after a majority of your gain stages, you'll stay tighter than if you added a similar-sounding amount of bass before them.
You want to add that bass later in the signal generally (EDIT: this is assuming that tightness is a goal. For early '90s kinds of downtuned death metal, where you need it to be a bit looser to get the right feel, none of this applies). Instead of going with a more bassy pickup, you'll be better off either turning down attack on that PD or turning bass up on your amp. The reason more bass can make your tone loose has nothing to do with the amount of bass frequencies on their own (bass amps produce more low frequencies than a guitar amp ever will and stay tighter in general...), but rather how bass interacts with your various gain stages. If you add the bass after a majority of your gain stages, you'll stay tighter than if you added a similar-sounding amount of bass before them.