Yep I actually just completed the install today.

Got this one over two years ago, sorry the link provided is from Amazon's UK page but apparently it's not sold in the US anymore:

GAMPRO Truck Air Horn 12V 150db 450mm Chrome Zinc Single Trumpet Air Horn with Compressor for Any 12V Vehicles Trucks Lorrys Trains Boats Cars: Amazon.co.uk: Car & Motorbike

Anyway it's a great horn albeit one for a boat! I had it mounted on a Jeep Patriot before moving it to the new 4Runner. Don''t have pics just yet but the install is straightforward. I used the same bolts for the stock dual horn mount just behind the grill, one for the compressor and one for the trumpet, and just angled the trumpet straight down. Only one connector is needed, just the passenger side horn wiring, battery, and ground. Painted it flat black before I installed it because I really hate chrome.

It's loud as hell and definitely gets people's attention when I need it. I've made a habit of honking at ever cellphone user I see.