If you think the old dog is down, look again. Here are some of the things being worked on. We all know about the Silent Eagle. But it's not real popular since countries would rather have the F-35 instead. And it only works on the frontal area only. But things like the conformal fuel tanks can be used on other versions of the F-15 including the newest based on the E models like the S and K. The F-15C models all use the PW-F100-220E engines that develop right around 23+K of thrust per engine with AB. But the introduction of the E model, they were offered with the PW-F100-229 which puts out 29K+ lbs of thrust with AB. This is the engine that went into the Korean and the Saudi F-15SA and K. This new engine uses the same techo from the F-135 and F-119 that goes into the F-35 and the F-22. But they have recently taken the PW-F-100 a step further and have a new engine available and are just now making it available. It's been offered to the new E, SA and Ks for a few more bucks. It has twice the TTOH than the normal 229 and produces over 31K of thrust with AB. Here is the rub. More Power doesn't mean more speed. The top speed of all F-15s won't change from Mach 2.5. If you wish to go faster than that, you had better have high temp leading edges made of either titanium or stainless steel. Right now, the only two manned AC with those features is the SR-71 with it's titanium and the Mig-25/31 with it's Stainless Steel. What the hotter engines gets you is the ability to accelerate faster and carry more of a load. Hence the 22 missile loadout of the F-15X and the massive ground to air ordinance. The new PW-F100-229EEP also uses less fuel for the same thrust. Just like the regular -229 did over the -220 and the -100 making the E model into a fantastic Tactical Nuclear Bomber able to fly from England to anywhere in Western Russia with a Nuclear Payload. Boeing is offering an upgrade to ALL F-15 models to upgrade it to 12 and 16 air to air missile payloads. 12 for the Cs and 16 for the E, SA and K. The F-15 has recently stolen the F-35 blind for much of it's Avionics. You would think that it would borrow from the F-22 but the F-22 is a generation behind the F-35 and the F-22 is likely to have to upgrade to the F-35 systems to stay current as well. The F-15 has a foot larger radar dome to work with and it's getting even more range out of the same power. The F-15 is getting the Link-16 installed as well so it can talk to the F-35. They are in the process of installing the Link-16 on the F-22 to make it compatible. I already stated that the F-15, as well as the SU-35, has reached the pinnacle of the manned fighter design. You can't really go anywhere past a 9.5 G turn for a few seconds or much past a sustained 7.5G turn. And both can exceed that. Even the F-22 has that limitations. So the improvements and mods to the F-15 keep it near or at the top no matter what is introduced in Manned Fighters.