Horsepower calculations based on ET never made sense to me. You can improve ET with changes that have nothing to do with HP or weight. The calculations based on weight and MPH are a better approach to estimating horsepower.
I scaled my 1320 with the aftermarket wheels & tires and fuel level well under 1/4 full: the car by itself was 4097. With me and and some extra fuel, it's definitely 4300+. HP calc'd for 4300 lbs at 113 MPH is right about 485, which is the factory rated net HP. That's very close to my baseline for "at sea level" corrected MPH with ETs in the 12.0 range.
2021 Challenger 6.4L Scat Pack 1320
100% stock: 1.680, 11.894 at 113.75 (DA 175 ft)
weight reduction, wheels, tires, Hellcat air box: 1.661, 11.686 at 115.97 (DA 710 ft)
1973 Challenger 452 ci street/strip [2008]
pump gas, DOT radials: 1.454, 10.523 at 126.44 (DA 514 ft)
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