13.5 inches is the perfect length for a 206 pipe. It fits perfectly between the top and bottom header brace. Do not put header sleeve next to the header flange (where it bolts to the head) This contributes to excessive head temperatures.
Withstands temperatures of 1200 degrees.
Fits the 206 pipes snugly.
Much easier to install than header wrap.
For more longevity wrap with safety wire in the middle and at each end.