Why Don't Modern Fighter Jet Hide Their Engine Exhaust?
While hiding the engine exhaust would make the aircraft more difficult to detect on radar, it would also make it less maneuverable. This is a trade-off that fighter jet designers have decided is not worth making.
The benefits of hiding the engine exhaust do not outweigh the costs. Fighter jets need to be lightweight, efficient, and maneuverable, and hiding the engine exhaust would compromise all of these factors.