[HELP] "setVehicleHandling" inconsistency

[HandBuzz]

For the past few days, I've been trying to improve the vehicles on my server. This included the desire of changing some vehicle handling flags. So I got working and wrote up this little "test script":

function vhandling ( theVehicle )
    if getElementModel(theVehicle) == 598 then
    	if setVehicleHandling(theVehicle, "modelFlags", 0x40002000) then
    		outputDebugString("model set")
    	end
    	if setVehicleHandling(theVehicle, "handlingFlags", 0x00404400) then
    		outputDebugString("handling set")
    	end
    end
end
addEventHandler ( "onPlayerVehicleEnter", getRootElement(), vhandling )

Now, this is executed server-side with the mention that both functions return true, which is bizzare since the modelFlags get applied while the handlingFlags don't apply. I've tried multiple hex combinations, none of them seemed to be working. If there are some of you who managed to customize said handlingFlags, I would appreciate to hear from you on this topic. I have tried multiple vehicle models with the same flag (for example SWING_CHASSIS) and none of them were actually affected.