My first question is why do you want to do a research year? Psychiatry is not like competitive specialties where research (or a whole year or two of research) are required or desireable to match, particularly for unmatched applicants. If you don't want to have a research career and aren't applying for research track residency positions, doing a research year is of limited utility to you. Psychiatry is a bit sensitive to being seen as a backup option (which it rarely is these days), though if you have strong board scores, clerkship grades and/or attend a top medical school these concerns can be easily allayed. The most important things beyond that is that you have a compelling answer to the question of why you want to be a psychiatrist and can describe your journey in a way that makes sense. Delaying graduation is great. Did you do any psychiatry sub-Is? One or two psychiatry sub-Is will be much better for your application, especially with strong letters of recommendation. Even if you have already done some advanced psych rotations, I would probably suggest doing some more if you have the chance and getting (hopefully) even stronger LoRs.
Spending a year doing research is not likely to help your application much at this point. Certainly not beyond anything else that would demonstrate commitment to specialty (be that in curriculum development, advocacy, policy, innovation, or other spheres).That said, it would not hurt to get some publications and presentations (e.g. poster presentations, oral presentations, or panels/symposia at psychiatry conferences), which can be accomplished without doing a research year.
