Something that cannot be stressed enough is that the performance of this product is STRONGLY dependent upon which throttle body is used. Although most people will commonly feel that a 75mm throttle body is overkill on a naturally aspirated 4.6L engine, our dyno testing, and the dyno testing of many others has proven otherwise. Prior to the release of this new plenum, even a 70mm throttle body was quite useless when using the factory upper intake plenum. In order to illustrate the differences in performance that can be seen using different throttle bodies, we have added a specific page dedicated to showing actual dyno comparisons of the most popular aftermarket throttle bodies, including a new 75mm unit from Accufab. From the beginning, we have stated that the 75mm throttle body generates the most horsepower when used with our new plenum. Put simply, the size and flow entry design of the throttle body determines the maximum airflow of the plenum, and therefore the maximum performance that can be achieved.