If they're flying the Mach Loop then you need to be in 25wing to get the manoeuvrability - it can be done in 45 wing but you need to allow for a bit extra. If you want to fly at high IAS then you sweep the wings to 45 wing and if you want to go for it then get them back to 67 wing! In 67 you get no manouevre flaps or slats and in 45 you get a partial amount - only in 25 do you get the full amount of flaps/slats and that is why you use it for the best manoeuvrability.
Cheers for that LJ. Understand the above just never seen a GR4 do it at 25 wing,
have even seen GR4's at 67
BW