Review on Zone Tech 12V Single Trumpet Air Horn - High-Quality Silver Single Trumpet Air Horn with Relay, Chrome & Compressor - Super Loud 150db for Trucks, Trains, Lorries, Boats, and SUVs by Adam Jenkins

Instructions are useless. Uses a T Tap and connects to the green wire from an existing horn on a 2004 and 2011 Silverado. Do not touch the black wire. Run a separate ground from the compressor to the floor on the truck (good ground on the bulkhead on the driver's side at the top in both years). You'll need to buy a wire, a ground loop connector, and a couple of connectors for the compressor. In 2004 we installed a horn on the bulkhead on the passenger side. In 2011 we will install it where the 2nd battery will be. Lightning hooked up the compressor in both. In 2011, the 15 A fuse blew immediately. I will update to 20a. Sounds good!