BHO takes 243x longer to complete than FB24, not 81x.
Made a hacked save, and found this. Compare these 2 images, and you'll see that FB25's days to complete is about 243x more than FB24's.
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Factor Boost 24 takes 1961 days to complete.
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Factor Boost 25 (or BHO FB) takes 476661 days to complete.
476661/1961=~243x.