The new ss 400 is not a durable bike and there are many resions for that, first of all it lakes safety of the rider because it doesnt have any ABS so if you rides it beyond 130 kmph the controling of speed of bike or instent breaking gets tough.
it does not have a traction control system so if you try to turn the bike or tilt it, it will get sliped.
bajaj motors tries best make a powerfull and fast bike but to keep it low cost they doesnot give any safety fetures in that bike for its rider.
the aerodynamics of the rider or the siting position of rider is not mantained aerodynamicaly so at higher speed it produces a grate amount of drag by which the engine has to work harder to take the bike at higher speed thus a slight decrese in milage is obtained.
all the body components are of typicle design so they are expensive.