Actually I’ve been quite curious about this argument about nozzle shielding, since the exit has are still extremely hot (unless mixed with cold air ducted from other places) and that will be bright in IR spectrum regardless of how well the nozzle itself is hidden?J-35 better have good nozzles cooling, structures are not hiding them. When we see the j-20 from the sides, we don't see the nozzles at all, tail and ventral fins hide them all, probably reducing IR signature a lot.