I have the solution!! Convert to BVH or Borg Warner auto!
Insulation of the outer cable is NOT useless. The factory used asbestos woven sheathing, there are many other more effective coverings available. When that sheathing is in place, or an effective insulating sheath is used, the proximity to the exhaust is a non issue.
With respect, I have had cables built which are in service today, lasting a number of years, through improved design and material considering the use.
When considering the cable, as the inner loses flexibility, no lubrication, then work hardens and eventually breaks, the difficulty of the cable to travel with the increased friction places further strain on the pivot.
Like I said; neglect and unknowing.