A fair bit to be honest, split the mesh into parts, then smoothing each part, then making sure they all fit together. I used a combination of Netfabb, Blender and Meshmixer.
I can get you a preview of the model if you want? unless you're already tackling the project on your own.
After some support removal, and being held in place, the fit is pretty decent.
https://i.imgur.com/emOKCol.jpg
as feared the rear of the safety cell has warped a bit, so will need some work to get the engine cover to fit properly.
https://i.imgur.com/t2re2Gm.jpg
The model details from the game are very good though.
https://i.imgur.com/AMoQqlH.png