No problems...I speak from experience. If you put it into manual it will shift it's self, first thur third @ 5800 RPMs. At this time ,is where you will either say ,fast enough or let's just see. In 4th ,if you shift @ 5700 you should be pushing 125 to 130. If you still have room, here's where you start thinking about your mechanical skills. If you are confident in that, 155 mph is where your beast will top out, going down hill you may see 158 and that's all you get! Have fun an if you do it , remember your not the only one out there. Things happen , you see it all the time.(In know way, am I ,or any one else, on this forum saying ,it is OK to ever exceed the maximum posted speed limit set by your local law enforcement agency).