Now you can let your engine really breathe! Stock throttle bodies restrict airflow, robbing power, especially from modified engines with large displacement and/or high-flow heads. With our 57mm straight-bore throttle bodies, you can increase horsepower big-time in Delphi fuel injected Harleys. A larger plenum area, longer short side radius for greater and smoother flow, and relocated nozzles for better fuel distribution are just a few of the improvements. Virtually all stock components are reused and will bolt onto the throttle body without any modification. Our throttle body is designed with the stock Delphi air cleaner bolt pattern so it will accept any H-D or Küryakyn air cleaner. It even allows you to retain your factory cruise!