HPi engineered a replacement 45mm throttle body to fit 2001-2005 Big Twin/Twin Cam Harley-Davidson® motorcycles, excluding 2001 Touring models. The upgrade will bolt to the existing stock intake manifold for an inexpensive upgrade complete with all the performance features of the HPi brand.  These features include a zinc coated throttle shaft, double sealed roller bearings and factory OEM bolt pattern. No dyno tuning or re-tuning required.