I would re-test the psa, making sure to use the same lab and the same assay as the prior tests, but abstaning from sex for at least 48 hours before the blood draw. I would have them re-test free psa at the same time. I would not take much comfort in 11% free psa, though there is some debtate about
the utility of percent free psa where total psa is <4. I would also ask the urologist to estimate the prostate volume, since a larger prostate will, ordinarily, generate more benign psa. (In other words, 2.8 psa is more concern in an average sized prostate than in a significantly enlarged prostate).
It might make sense to do a PCA3 too, as you suggest. However, there are some issues regarding PCA3, including determining the appropriate cutoff to use. (The higher the cutoff, the greater the specificity of the test, but the lower the sensitivity). If this does not make sense to you, let me know and I will explain.
In your BF's situation, I would personally do the PCA3. However, if the bpsa has increased over 2.8 upon re-test, then I would do the biopsy unless both the percent free psa and the PCA3 indicated low risk. Of course, that is just my judgment, and others could reach a different conclusion. But my own thought would be that, for a young guy in good health, there is significant value to diagnosing p ca, if it is there, within the "window of curability."
One final comment: You say your BF's total psa is only slightly higher than the 2.5 psa that is typical for his age. It is not true that a psa of 2.5 is typical for a man in his early 40s. It is very high for a man of that age -- certainly in the highest 5%. A typical psa for a man in his early 40s would be around .6. That does not mean your BF has pca, but it is certainly high enough to pay attention to.
Best wishes,