yes it needs to be done via a remap
i know there are remaps in the us for your cars, but they arent like the turbo remaps world wide...
i can specify any speed to have the cut set at, although 99.99999% of re mappers in the uk cant do this for you as they just upload a program they have stolen from someone else...
talk to the remappers in the us, and if they have infact developed their own remap they can then change the limit, if they havent then they cant help you cos they have no idea and are just selling s file that was emailed to them from europe...
but yes it can easily be done..
i had just the limit increased on mine as they tuner was still developing the map, and when he was finnished then the full remap was uploaded, but in the beginning just the limiter was edited