...a narrower hand position will help you keep your upper back a little tighter and more stable. When you bring your hands in, your scapulae naturally have to retract harder (so your middle and lower traps will be tighter, along with your rhomboids), and your shoulders will naturally have to adduct (tensing your lats a bit)...In general, your hands should be as close as you can comfortably get them. If you can get them closer without pain in your wrists, shoulders, or elbows, or just feeling super uncomfortable, then you’d probably benefit a little from doing so.