The 41005 is a shorter header and combined with the 86 series pipes, the overall length is too short for the engine to scavage properly making it feel very flat on bottom or what can be described as a lean bog or clutch bog. The shorter 41005 header combined with the longer 9853 tuned section or the longer 41021 header with the shorter 9886 tuned section will have a little different running characteristics but because the overall pipe lenghts are similar, they will both tune and perform pretty well. It will be a personal preferance as to what you prefer for overall power delivery characteristics.