Both the Soviets and Americans hung pulse jets on the wings of fighters as experiments. For the Soviets they hung a pair of ramjets on the La-126 (developed from the La-120/La-7) and on the La-138. A number of La-7s and La-9s were fitted with pulse jets.
P-51s also were tested with ramjets and pulse jets.
In every case, the gain in speed was more than offset by ill-handling.
My regards,
Widewing