Originally posted by TurboS10
You are confused. Smaller pipes are generally used on engines that need less air flow and are generally lower end type engines. Engines that make power consume more air and need the larger exhaust tubes. Air flow is related to engine capacity and output more than power band. You are not going to kill low end torque with larger than needed pipes, but you will kill high end power by putting a section of small pipe. The pipe will only flow as much as the smallest section.
stepped headers work in this way to boost low end power and still maintain midrange and upper. Backpressure is important for torque production TurboS10, very important. By going with bigger tube headers and big exhaust you can loose alot of getup and go from a small motor, so saying that you are not going to kill low end torque is a lie. It may be more evident if you use smaller than needed pipes that restrict flow and kill top end, but finding the balance is the key.