The Adder now has the following modifications to go accordingly to the Veyron.
-Top speed of 255 mph
-Suspension and grip improved to handle the high speed and lateral G's.
-The car now has realistic deformation.

The instructions are in the Readme, including a way of implementing this mod without erasing other mods that use the handling metadata file.

You need Open IV to install this mod.
This is a very early work in progress and I intend to take this project till the implementation of the 3D model when Open IV has the capability to edit those files.

Here is a video of how it looks.
https://www.youtube.com/watch?v=i2j4PHbKJD8