Lockheed has figured out how to increase the missiles carried by the F-35 stealth fighter from four to six. This was difficult because the missiles must be carried inside in order to maintain stealth. A rack adaptor allows them to add a second missile onto each of the outer stations of the internal weapons bays.
Boeing is trying to sell an improved version of the F-15 called the F-15X. The F-15X carries a lot of weapons.
SOURCE – Breaking Defense