For what it's worth, here are some magazine times for various SRT models:


300C SRT-8, Road & Track Magazine June, 2005 issue: 0-60 in 4.7 seconds and 1/4 mile in 13.2 seconds.
Charger SRT-8, Motor Trend December 2005, 5.0 and 13.5.
Magnum SRT-8, Car & Driver September 2005, 5.1 and 13.6
Jeep SRT-8, Motor Trend February 2006, 4.8 and 13.5
Challenger SRT-8, Road & Track July 2008, 4.7 and 13.0
Challenger SRT-8, Car & Driver December 2007, 4.8 and 13.2

Car & Driver tested the Crossfire SRT-6 in August 2004 and got 0-60 in 5.1 and 1/4 mile in 13.3.
In Road & Track's shootout with the Crossfire SRT-6, Nissan 350Z and Porsche Boxster S they got 0-60 in 4.8 and 1/4 mile in 13.3 for the SRT-6

It looks like they're all pretty close, so depending on driver, track prep, tires, weather, altitude, etc it should be a crap shoot. Nice thing is with a boosted car you can easily add more boost and be faster. All those SRT-8s are naturally aspirated so it takes a bit more to add power.