First, both Q48 and V38 are excellent scores, and if you extract the inflated Q scores from one particular country, those scores correspond to nearly identical percentiles, and it's percentiles that matter. So you're actually doing roughly equally in Q and V. But there's another important factor: how much improvement you'll likely see by studying Quant further, and by studying Verbal further. Very high Verbal scores are very hard to improve upon, because the skills tested in, say, high-level RC questions are skills we build over years, not over weeks. I'm also not aware of any prep material on the market that is designed for people with Verbal ability as strong as yours. So while you should likely still devote some time to Verbal (and that is especially true if you stand to improve at SC, which you can improve at with study in a short space of time), it's more reasonable to expect an improvement in Quant if you study effectively.
At your level, taking any general prep course will not be a good use of time or money. Courses generally need to proceed at the pace of the lowest level student in the class, and courses need to cover all of the foundations for students who haven't done any preparation yet. You already have all of that foundation if you're scoring a Q48. Instead, you'll want materials or instruction specifically intended for high-level test takers. If you haven't already, I'd suggest getting the official advanced question book, for example. If you want to invest in actual GMAT instruction, the only option that will likely help is private tutoring with a tutor who specializes in working with the highest level test takers. If you want to self-study, you should seek out materials specifically intended for high-level test takers. I've written a set of books, and a batch of very challenging problem sets, that are meant for test takers in the Q40s aiming for Q50-Q51 scores, and if you might be interested in those, feel free to message me or email me at the address in my signature. You can quickly get an impression of how I teach GMAT math by reading some of my Quant posts on this forum. Good luck!
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