[ElfJedi]

I never played "Titanfall" but bought this Jester 7" figure for the brilliant design (also makes a cheapy Chappie!)
I added articulation to the waist, which SHOULD have been there in the first place & it worked out OK - so it CAN BE DONE!
I'm a new member here & a newbie customiser, so apologies for the rough approach but suggest this is for an intermediate or better customiser.
I'll try & post more detailed Customising notes in the Customs section PLUS photo link (if allowed), but summary of steps below:

1/ The entire top torso CAN be removed - carefully separate with a hobby knife.
2/ Remove the vertical pre-posed "spine" at the back (pre-posing is heresy) + temporarily detach the 2x orange & 1x black cables.
3/ Cut off some of the top from the right vertical front "rib strut" to match the height of the left one - keep these side struts in place.
4/ I used a black Revoltech 'double-hinge' joint for the new spine which fits the waist gap perfectly (from eBay mixed bag of Revoltech joints ~$10).
5/ Drill a hole in the top & bottom plates to take the Revoltech joint tips.
6/ Re-position the cables from '2' into new holes in the top plate.
7/ Push the Revoltech joint into top and bottom holes (not glued to allow movement) then either glue top plate back into the chest or use a screw like I did through the top plate into the chest for improved strength.

Voila - improved waist articulation for forward & backward plus waist twist movement (no side to side tilt yet) - still better than the fixed pose ANYDAY!