Tootin’ My Horn: Upgrading to a Dual Horn Setup


The stock Mazdaspeed 3 horn does not fit the car’s aggressive looking profile. Instead of a booming, attention grabbing blast, the stock unit sounds like something that belongs on a clown car in the circus.

Obviously, a change was needed.

I had been looking into changing the horns for some time. One of the reasons I held off changing them was the amount of tear down required to install them properly, as well as the daunting challenge of wiring them in properly so that they work. At least so I thought. Removing the bumper cover, I discovered, was easier than I thought. Wiring them in? On the Mazdaspeed 3 it is actually very simple. With those two conditions out of the way, what was I waiting for? I decided to finally dive in and install a set.

Choosing New Horns

After deciding that I was ready to change my horn, I then had to decide what kind of horns to install. There are a lot of choices, with the most popular being the Hella Supertones ( The Supertones are a dual horn setup, with a low toned horn (300 hz) paired with a high toned horn (500 hz), rated at 118 db. For comparison’s sake, the stock horn is ~ 85 db.

Sickspeed Performance Dual Horn Setup

The horns that I actually decided to use are from Sickspeed Performance ( There are very similar to the Hella Supertones spec-wise, rated at 118 db. The reason why I decided I to go with the Sickspeed horns vs the Hella Supertones is that I got a very good deal on the Sickspeed horns and decided to give them a try.

The Sickspeed horns came nicely packaged in the box, each horn came already equipped with a mounting bracket, but no other installation hardware. A wiring harness is not included, but you can purchase one from the Sickspeed website. Included in the box was a simple wiring diagram, stickers, and a flyer advertising more Sickspeed products. The horns themselves were a nice size, 4.8″ in diameter. Keep that in mind when trying to find a place for these to fit, there are a bit larger than the stock horn they are replacing.

Pre-Installation Prep
Up close shot of one of the Sickspeed horns.

Installation is pretty straightforward, you will need a socket/ratchet for attaching the horns to the car. I did not order a wiring harness, so you will need to make a run to the parts store for some items if you do not have them on hand already: 16 gauge wire in both red and black , 16 gauge male and female spade terminals, 16 gauge scotch/snap locks, a 16 gauge ring terminal, wire crimpers, and wire loom (the loom is optional).

Wiring It Up

The way I wired up my horns allows the vehicle to be returned to stock quickly. None of the stock wiring was cut or modified in any way. First thing you are going to need to do is to make a power wiring harness. Decide the mounting location of your horns, you are going to need to know the distance between them to determine how long this wire needs to be. The next length of wire that needs measurement is the one that runs from the stock horn’s power line, to your closest horn.

Power Harness
You will need to make two wires like this. I made one with red wire (power) and one with black wire (ground). The only difference between the two is that the black wire gets a ring terminal on one end.

Connect a female spade connector to one end of the longer wire, crimp it, and then connect that to one of the spade connectors on the farthest horn. Next add another female spade connector to the other end of the wire, crimp it and then connect it to second horn, matching the spade used on the first horn (i.e. looking at the back of the horns, if on horn 1 you used the first spade, on horn 2 you would use the first spade). Next, take the shorter wire and a scotch lock, and connect it to the wire now running between the two horns. On the other end, attach a male spade connector, crimp it and then slide that connector into female end of the stock horn wiring harness.

Ground Harness

For the ground side, you will be doing the exact steps for making the power harness, with the only exception being instead of adding a male spade connector, you will add a ring terminal instead. There is a chassis ground on the passenger side of the car by the washer fluid bottle that you will attach the ring terminal to. That will provide a sufficient ground for the harness you just created.

I ran both of my lines through plastic wire loom, it is available at any auto parts store. I do not think my wires will rub on anything and break, but I decided to take the extra step just in case. I will leave this up to your own discretion as an optional step.

Double check all of your wiring and ensure everything is secure, then give the horn a test. If done correctly you should be greeted with the sound of (a much louder) horn!

Final Thoughts

Upgrading the horns on the Mazdaspeed 3 was an easier process than I thought, especially because there wasn’t a need wire in a relay. It is something that can easily be done in an afternoon, and the end result is that other vehicles will CLEARLY hear your horn now when you need to use it!

Just remember: with great horn comes great responsibility!