Why wont my 2003 mustang GT go past 120mph when i accelarate it stops there?
I don't know where you people are getting your info. But the new edge GT's definitely do not have had governors on them, rev limiters yes, but there is no speed limiters on them The V6's might be governed to around 107-112 for tire speed rating considerations. But the V8's are not. When my 03 GT was stock It exceeded 130 MPH and had a little more in it before I ran out of road.
As for why you're topping out at 120 MPH, if you have the stock 3.27, you should be shifting into 5th at about 125 MPH. If you're shifting into 5th at lower speeds you'll drop the engine into a lower RPM range where it doesn't produce as much power. The P.I. 4.6L in the Mustang makes it's peak torque around 4000 RPM and the HP peaks at just after 5000 RPM. When you take into consideration that the 5th gear is either .62 or .68, there's a lot RPM drop off when you shift into 5th. If you're only turning 3200 RPM in 5th gear (which equates to around 126 MPH on a stock 03 GT), it's going to take a while to get the last 10-15 MPH out of the car since it's out of the RPM range where the engine makes most of it's power.