I thought the picture with "I can catch that Me-262 now!" was a fake,
but it was real!
Amazingly, two P-51s were fitted with jet engines.
The first had pulse jets, based on a German design, under the wings.
(Information about the speed boost and when it was made isn't available.)
The second had US Marquardt ram jets on the wing-tips.
Speed was boosted by 50 MPH and was made in 1946 (after WWII).