I have hit 172mph in my SRT6. That's the fastest, but on another occasion I hit 150 and 160. I know because I have a GPS that reads out speed. My car is factory as far as I know. 2005 SRT6: UPDATE: I put true dual exhaust on the car and achieved 178mph. There's a video on YOUTUBE and the guy takes a video of his car's speedometer and he shows 179mph... no not kilometers. I actually believe I could have gotten above 180 as I was at about 5800 rpm and my rev limiter is set for 6300 as well as speed limiter has been eliminated. I have seen a couple calculations on what actual speed the SRT6 could achieve assuming minimal wind drag, and at 6300 rpm, and 5th gear, it calculates out t0 188. I also have seen another calculation of 194mph. Either number is very impressive considering the price and minimal improvements required to turn these cars into race cars. I do have the Eurocharge pulleys and computer flash. My next item is going to be the Needswings intake and I am forever done. I now plan to just keep the car from blowing up. I think these things are fragile and susceptible to all kinds of silly electrical problems. I have one literally at this minute with charging system. Acceleration causes alternator to stop charging.