I am not a fan of straight pipes on anything. The Thunder Header actually makes a shit load of power compared to most other exhaust systems on the market. The majority are just to look good. My bike (1200) made more torque with that setup than my fathers Road King, and he had the same intake with slip on Vance & Hines. We both were running power commander III. I have dyno sheets somewhere, cant seem to find them right now.