While I don't agree with the OP driving during the day with other drivers (I'd have done it early in the morning) I don't see why the new SRT8s cant get above 170, back when I first got my SRT8 I was driving from Hampton to D.C for work and I hit 180 with no tune, it was in my EVIC for the longest time as being my highest recorded speed until I just had work done recently and it was reset with a battery disconnect. Took F-O-R-E-V-E-R to get from 170 to 180 though... Don't remember how long but it did hover around 178 get to 180 then drop to 179-180, 178 etc... aerodynamics FTL.
My run was done @ 3AM with zero traffic (didn't see a car the whole time, and for a long time after).
2007 Charger SRT8 - YSi and more. MPR Built