Among other things, Bong, McGuire and others knew how to use ‘differential throttling’ to make the P-38 turn faster, they would retard the throttle on one engine and advance it on the other to make it turn faster. As a result, the P-38 could turn a lot faster than Japs expected.
Lindbergh also helped P-38 pilots development methods of extending range. He bagged a few Japs, too, even though he was a civilian.
Lindbergh also helped Marines with the Corsair teaching techniques that allowed it to carry a heavier bomb load.
He wasn't popular with combat squadrons because he insisted on going on combat missions with them and nobody wanted the publicity that would go with being the guy that got Lindbergh killed.
He officially shot down a Japanese Ki-51 Sonia, a single engine light bomber, although there are rumors of others.
The Japanese home defense air squadrons were so amazed by the P-38's dogfighting skills they nicknamed it the "Fork-Tailed Devil."