What if the aircraft is already flying at M2.5? Would the entire fuel be used in VFDR mode and would the range be increased? - like maybe an F-22 on AB.

To continue on what I was saying:
- the F-22 has good strike capabilities. It can carry 8 SDBs. From what I read the F-16 block 25 are used mainly for a/a. They will not be equipped with SDBs. They can't even carry JDAMs.
- the F-22 could carry a/g weapons on external stations. Up to 24 total SDBs could be carried when stealth is not required.
- The F-22 is much more lethal than the F-15C. 160-180 F-22 are the equivalent of at least the double of F-15, that is about 350 F-15s.
- the F-15Cs could be armed with FMRAAMs even without APG-63 V(3). The APG-63 V(1) is still a good radar with a good range, and the FMRAAMs could recieve their targeting information from F-22s through the FDL. Arming the F-15s as they are with FMRAAMs would already make them significantly more lethal - and survivable.
- the B-2s can carry 80 JDAMs.
- the B-1s and B-2s will soon be able to carry about 200 SDBs. That's the same number of PGMs as 50 F-16s ( 4 PGMs per F-16 ).

I didn't work today so I had time to think about things that are very useful.. ahahah

No. The VFDR is structured such that ~2/3 of the fuel volume will ALWAYS be expended in boost. If you look at the Meteor cutaway, it'll be the section to the aft of the "interstage" and valve. When you light the Meteor, the aft 2/3s of the motor burns just like a rocket. Once that empties out, the fuel rich sustainer cuts in and burns with air from the intake. You can't take the boost fuel grain and have that do something else.

What will happen though is that the booster burn out velocity will be higher and the VFDR take over speed will consequently also be higher. The same applies for the solid fuel rocket. The portion of the motor designed to produce very high thrust for a short duration will always do that regardless of launch speed. The sustainer will always burn at it's prescribed rate, again, regardless of the launch speed. You'll need to go back to the drawing boards to change that.

If you are to design a VFDR missile is designed to burn all of its fuel in VFDR mode, you'll have a missile which cannot be launched unless the aircraft reaches Mach 2.5 before firing and the acceleration from Mach 2.5 to say Mach 4 may be painfully slow. It will however, go a lot further!

I guess that could be an idea for the F-22 for long range engagements, especially since the F-22 is said to be able to supercruise at M2. The booster could be cut in half or something. The missile may not fly as fast but it's not a big drawback since the target would be taken by surprise most of the time.

Max range would be increased to what 250km?

The F-22 program has not cost 300 billion it has cost around 50 billion.

Like dwightlooi said, such a long could not be used in 90% of the flight enveloppe. However 2 versions of FMRAAM could be developped, one "general purpose" for all the other fighters and one extra long lange for the F-22. The F-22 could carry a mix of the two, just to be sure it always has something to launch. The R&D cost of a second version would be low since it would be basically the same missile but with a different fuel ratio.

That sounds like a good idea, even though I'm not not sure that 6 could be carried internally. Correct me if I'm wrong but the AIM-120Cs are carried in diagonal to be able to fit 3 per bay. I don't think you could do that with the ESSM.

If it's not possible for sure a mixed configuration could be used, like 2 ESSMs in one bay and 3 AMRAAMs in the other to have more BVR shots.

That sounds almost perfect. The missile is heavier but it's very acceptable. It would have roughly the same range as a phoenix but at half the weight.

They could even modify the 4 missile canister to make it stealthy for external carriage. Each pylon is rated at 5000 lbs so it's well enough. The canister and the pylon could be jettisoned when empty to reduce RCS and drag.