TTi dual exhaust '67 dodge dart

I too have 3" TTI kit in my 69 Dart, been driving it that way for 6 years no issues. Also running 3/8" fuel lines, and offset spring hangers. One issue I am now having is slight interference between recently installed CalTrac split leaf mono spring and tailpipes.

As was said earlier, not enough heat in the tubes back there to cause issue with fuel tank. Make sure you have clearance for a little movement, and nothing is rubbing. If you are bothered by this, do as suggested and fab a heat shield, or wrap the pipes with thermal wrap. Be aware thermal wrap will hold moisture and cause corrosion.