You only need a little common sense to get what I am saying.
You seem to have a little idea that inlets are bad for stealth. But what about the engine?
Do you see what's wrong with this engine?
Just like how inlets are bad, engines are actually even worse. And if you don't have an engine that has blockers of its own inside, the aircraft is as stealthy as a barn.
Without the J-20 getting new engines, or at the minimum an engine with a blocker, it's of little to no threat to modern SAMs.
The J-20 has some advantage from the front, and that affects other aircraft at co-altitude, but it doesn't affect SAMs because they are all looking up and will receive returns from the J-20 due to cavity resonance and edge diffraction from the engine.
Also the SAM emplacements in the Himalayas are unique. You will find radars facing towards your own territory in order to be safe from artillery fire and catch aircraft while they are ingressing into your own territory.
The J-20 is a good aircraft. But without a new engine, it's not all aspect stealth and is not a surmountable threat to modern SAMs.
This is the F-22's radar blockers in the engine.
What was that about S-ducts again?
I gave up replying to you because you didn't get something so simple and I didn't want to waste time talking to people about it when they understand so little.