If they don't show stealth technology how can you say GTVA's is more advanced? For all you know there is a stealth ship that you haven't detected.
And Shivan sensors seem to be so advanced they don't need AWACs in the nebula.
I'm using logic + evidence to support my IDEAS (you can't say the Shivans are more advanced in stealth UNLESS they ACTUALLY SHOW PROOF THEY HAVE STEALTH TECHNOLOGY). You should try too, it's good for the brain
Yes, it's possible Shivans have stealth tech, but EXTREMELY unlikely, seeing as how it doesn't match their style. Shivan tactics are quite simple actually:
-attack with several ships and fighters
-several ships + fighters die, send more ships & fighters, and bigger ones at that
-bigger ships die, send even bigger and MORE ships
-if all else fails, call in a fleet to distract and supernova the system
Their defenses seem to consist of this:
-a few wings + sentry guns guard a depot/comm relay/gas miners
-get attacked, call in more fighters
-reinforcements die, call in some more fighters and a cruiser
-still fail, sending a giant team of dragons + destroyer (or juggernaut) to wipe the attackers out
The Shivans aren't as almighty as you may believe them to be. After all, they are only a 'symptom' of a bigger problem. This you can't really dispute.