What is the maximum speed I could reach with aftermarket modifications ? My cousin had a 1998 honda civic blocked at 190 km/h. He added a chip and a tuner on it and it brought the car at 230 km/h. A 1999 to 2004 mustang is blocked at 240 km/h. But with modifications without installing a supercharger or a turbocharger, what is the maximum speed I could reach ?