Looking for advice, BB headers vs. HP manifolds

I saw a test where 3in. exhaust picked up a good amount on a stock 440 6 pack. Of course it was a flowmaster add. Take it at what its worth. I was thinking like 30+ hp over stock exhaust. HP Mopar did a drag test on tti 2.5 and 3in. ex. And the 3in. was worth almost a tenth over the 2.5 on a mild 360 but it did have headers.