There isn't a range extender similar to what is used on the vision/vision+ for the P2 non vision. Extending the range of a P2 NV is done with high gain antennas.
The V/V+ are on a different frequency.
For us NV flyers, the modification consists of removing the white controller antenna and replacing it with a wifi-router type antenna with higher gain.
Have a look in the modifications part of this forum, there's lots of info. Youtube also has lots of tutorials.