Turbosmooth is activated by clicking on the light bulb in the modifier stack.
In the OBJ file, turbosmooth add optional
Who works in VRay version lower than 3.1 be careful, in some materials in the BRDF section is Microfacet GTR ( GGX ), if Your version is older than 3.1 , then the BRDF field will be empty. Select the Blinn, Phong or Ward.