At the 6200 RPM redline the SRT6 should top out at about 188 while the non-SRT6 should top out at about 178 if there was no electronic limitation on the speed. The top speed doesn't depend on the supercharger, only on the engine RPM, transmission and differential ratios, and rear tire diameter. For any given RPM, the SRT6 should be about 6% faster (3.25/3.07) since only the differential ratios are different (I'm assuming the transmission is the same). The supercharger just helps you get there a lot quicker.