JMM, don't worry too much, as worrying never really solves anything. If you get a B+, don't take this as the "end" of your PhD application process, which you haven't really started yet (I'm assuming). My advice is to get the best grades that you can. If you can get an "insane grade" on the final, then do so! If you get a B+ overall, that's ok too. Research experience, fit, grades, GRE scores all play a role - the extent of the role depends on the program and what that school is looking for. Just ensure that your application overall is A game, apply broadly, and you should be fine. Don't worry.😎 Be happy!😀