Kenne Bell was first to use the 75mm on a 4.6 GT. 70mm/Big Tube Kit is up to 20HP gain. Both will fit "Big Tube" kit. Kenne Bell 90mm highly recommended with either throttle body. Polished billet aluminum. Designed to fit Kenne Bell manifold. 75mm won't fit stock manifold.
See "99-04 Tech" for more info.