Onservation about magnum 5.9

I like to think I'm pretty familiar with LA 360's and magnum 5.9 performance having put hundreds of thousands of miles on both and daily driving a 5.9 pickup.
But as my dart gets closer to driveable I've taken a few rips with it in front of the garage for fun.
I noticed that this junkyard 5.9 with a cheap air gap style intake 750 edelbrock and old spitfire headers revs much,much quicker than any of the carbed la 360's I ran and far quicker than the injected 5.9s.

I can only surmise the factory kegger intake and cast exhaust manifolds are very restrictive.
I'm really not sure. But I had to try hammering on it a few times to be sure.

I wonder how much better m

y truck would tow and haul with headers and a better induction setup?