im playing a MIM fender p bass, and i like the tone i get out of it with my distortions/amp, but i can't help but wonder if an improved pickup would be worthwhile. the bass is downtuned and im interested in having a really aggressive doom sound (exg: i cant stop listening to Nostos Algos by Thrones). the seymour duncan spb-3 has seemed like a good choice by looking at it. however, i have heard from many that for heavier music that amps will make a far greater impact on tone that pickups, and that the seymour duncan would not be fully worth the money. any of you guys have some input? also, i've thought to myself about how fun it might be putting another pickup (p or otherwise) between the original one and the bridge. how expensive would this be to have done in a shop?