At the track my 06 GT stock clocked 7.4sec 0-60, or 7.8sec 0-100km/h.
That was with 1/3 tank of fuel, spare tire removed, tires at 50psi and I brought the engine up to ~3500rpm before dropping it into gear with a quick chirp of the tires and traction control off. Everyday launching from a stop I estimate mine to be close to 8 seconds flat.
With your mods I'd say you'd be in the 7.1-7.3sec mark depending on your launch. Street start should net you an easy 7.5 seconds. Your 08 has some extra OEM HP as well over my 2006. Your 08 might even break into the high 6's if you keep weight down and your tires aren't slippery.
A lot of folks don't consider their own weight either - a car with a 150lb driver, versus a 350lb one will make a difference.
'11 Ram SXT 4x4 quad cab - 5.7L V8; 128,200kms
'09 Malibu 2Lt 3.6L - 140,000kms purchased 1 March 2019
'06 Pontiac G6 GT - 3.5L V6; 162,000kms (rear ended 15 Feb 2019, and given totalled title by insurance)