Terry Accelerator cable

[ahklein]

I need to replace the accelerator cable in my 76 914. I purchased the Terry cable from our host. It looks high quality and moves very smoothly on the bench. However, it has no inner sheath as the OEM did. What happens over time as it must make a bend at the rear of the tunnel? It must be rubbing against the metal tube. Won't this fail? If it were a straight shot I would not be concerned. Anyone use this successfully? Thank you for your input.