That may be true, but I don`t know wht makes you so sure that the "west" is so far ahead.
The US may be, but UE is not...i think the EF is 4+ generation, not five, and it`s not being produced. I don`t now what BVR will be for stelth fighters, as useing them would give them away, but for now I haven`t heard of a real fight with Su27`s and fighters from US(or Israel). The Su-27 has electro-optical devices for targets as far as 40 Km(not dogfight range) and it`s termical signature is low.