Known the world over under various names such as Velocity Stacks, Air Horns, Trumpets or Ram Pipes they allow you to "tune" you engine in a relatively simple way and this particular version is a 50mm "tall" top quality machined alloy bolt-on trumpet for 40mm diameter carburetors.
So, these trumpets measure 50 mm in total length and feature 65 mm stud centers and will fit, amongst others, the following carburetors:
This product is priced and sold as a single unit.