Old drag racers rule of thumb, every 100 pounds you take off the car lowers quarter mile time by a tenth of a second. Other variables to consider, driver weight compared to the test driver in the tests you read about, anything else you might have in the car, and the biggest variable, driver ability. I have seen the same car driven by two different drivers, same day, same conditions, and the quarter mile time vary by over a second in the quarter mile.
2013 GT 6 spd, GT500 mufflers, BOSS quad exhaust, Roush CAI, Barton shifter & 2 post bracket
CS GT-40 Wheels, Hotchkis sway bars, upper and lower control arms, springs (1.1/1.6 drop) and adj panhard bar KONI yellow struts and shocks J&M caster/camber plates,
BMR Upper control arm mount and lower control arm brackets.