For sale is a used Black Thunderheader. Model 1031B. It has the 18mm O2 sensor bungs, would work with the 18mm to 12mm reducers. The pipe is in good shape, no damage. It has the typical Thunderheader finish and has some flaws, but good overall. The bracket is in excellent shape, no cracks. I did do the "Thunderheader mod", so two of the fins in the baffle have been bent out. Helps with low end torque. See pics. The blue tape is just theres so the bracket doesn't slide around. $450 shipped to the lower 48. PM if interested.

 

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