THUNDERHEADER EXHAUST - DYNANOTE: ALL EXHAUST SALES ARE FINAL AND HAVE A 12 WEEK MINIMUM LEAD TIME. NO CANCELLATIONS, REFUNDS, OR RETURNS. Ramjet's has been selling Thunderheaders for nearly 30 years! Shortly after being introduced to the market in the late '80s, Thunderheader 2: 1 exhaust systems became THE performance exhaust system for your Harley Davidson. Between the unmistakable Thunderheader sound to its seat of the pants, dyno proven performance gains, and its iconic