The wirecutter DIY test used a filter with a rating of FPR 9. Since FPR isn't standardized like MERV or HEPA, it's hard to tell what this means, but likely to

The wirecutter DIY test used a filter with a rating of FPR 9. Since FPR isn't standardized like MERV or HEPA, it's hard to tell what this means, but likely to be < MERV 13. The OP used a HEPA filter on their testing which is > MERV 16.