100 pound loss = how much HP gain???

I'm already doing it with my Duster.... 1320 divided by 99 mph = 13.3's. Exactly what it runs... and I'm doing it with 2.94's/stock converter in 100% street form - all which adds to the difficulty..
I haven't heard that run down before thank you for letting me know..
I wonder what it would do with 5200 converter and 4:88 gears?...