Try to set 1 instead 0 in mesh cockpit (enable individual cockpit mesh).
[SYSTEM_TWEAKS_ENABLE]
HeadViewMove = 1 ; set to 1 to enable head view movement tweak
HelmetMoving = 1 ; set to 1 to enable helmet moving sensitivity tweak
OnboardCamera = 1 ; set to 1 to enable onboard camera position tweak
OnboardCamEdit = 1 ; set to 1 to enable onboard camera position edit mode
ViewAngleCam = 1 ; set to 1 to enable onboard camera view angle tweak
ViewAngleEdit = 1 ; set to 1 to enable onboard camera view angle edit mode
HelmetPos = 1 ; set to 1 to enable helmet position tweak
HelmetPosEdit = 1 ; set to 1 to enable helmet position edit mode
SteerPos = 1 ; set to 1 to enable external steer position tweak
SteerPosEdit = 1 ; set to 1 to enable external steer position edit mode
ArmsPos = 1 ; set to 1 to enable driver arms position tweak
ArmsPosEdit = 1 ; set to 1 to enable driver arms position edit mode
CptSteerPos = 1 ; set to 1 to enable cockpit steering-wheel position tweak
CptSteerPosEdit = 1 ; set to 1 to enable cockpit steering-wheel position edit mode
CptDashPos = 1 ; set to 1 to enable cockpit dash position tweak
CptDashPosEdit = 1 ; set to 1 to enable cockpit dash position edit mode
ArmsColors = 1 ; set to 1 to enable arms color tweak
RimsColors = 1 ; set to 1 to enable rims color tweak
TyrePos = 1 ; set to 1 to enable tyre position tweak
TyrePosEdit = 1 ; set to 1 to enable tyre position tweak
CptSteerLock = 0 ; set to 1 to enable cockpit steerwheel rotation locking tweak
QualRules2003 = 0 ; set to 1 to enable 2003 qualifying rules tweak
Pitstop = 1 ; set to 1 to enable pitstop timing tweak
RearLightBrake = 1 ; set to 1 to enable rear light braking tweak
AmbientPos = 1 ; set to 1 to enable rear light ambient position tweak
PitLimiter = 0 ; set to 1 to enable pit limiter tweak
SpeedLimit = 1 ; set to 1 to enable pit speed limit tweak
HelmetVisor = 1 ; set to 1 to enable visor on selected view modes
RainDroplet = 1 ; set to 1 to enable rain droplet on selected view modes
CarsEnabler = 1 ; set to 1 to enable car enabler tweak
SlipStream = 1 ; set to 1 to enable slipstream effect
SlipPlayer = 1 ; set to 1 to enable slipstream affect to player car only
FFEffect = 0 ; set to 1 to enable force feedback custom effects (GP4 v1.02 only)
FFEffectGP4v100 = 0 ; set to 1 to enable force feedback custom effects (GP4 v1.00 only, may not working properly!)
CustomVisor = 1 ; set to 1 to enable custom visor tweak
VisorDirtEffect = 1 ; set to 1 to enable dirt effect tweak (CustomVisor must enabled)
VisorDirtPlayer = 0 ; set to 1 to enable dirt effect drawn on player car only
MeshSteering = 1 ; set to 1 to enable individual steering-wheel mesh
MeshFrontWheel = 0 ; set to 1 to enable individual front wheel mesh
MeshRearWheel = 0 ; set to 1 to enable individual rear wheel mesh
MeshHelmet = 0 ; set to 1 to enable individual helmet mesh
MeshCockpit = 0 ; set to 1 to enable individual cockpit meshTyreWear = 0 ; set to 1 to enable adjustable tyre wear
MeshProtect = 0 ; set to 1 to enable encrypted GP4 *.gp4 mesh file supports
TextureProtect = 0 ; set to 1 to enable encrypted GP4 *.tex texture file support