Took me about 2 hours to install. I used as much of the already existing hardware on my 1998 Ford Expedition as possible. (see customer pictures and corresponding notes) Another reviewer mentioned spending 300 to have it installed professionally, which is ridiculous. It really wasn't that hard to install... I think he got ripped off.

The sound is exactly what I expected based on the "Check out related media". It is a lot louder than the stock horns, but I still wish it would have been a lower frequency.

The only thing that bothered me about the installation was mounting the compressor. The bolt that secures the compressor to your vehicle spins freely as you tighten the nut, and considering how cramped the area was where I installed the horns, I was getting pretty frustrated trying to tighten the nut/bolt.

After several days of driving along careless a*holes driving SUVs (which and neither "Sport" nor have any "Utility" in them, except to bully their way through traffic), I've decided to buy the Wolo 417 Long Dual Air Horns. It was a huge challenge to install them inside the front fender of my 02 Volkswagen Golf GTI alongside the OEM dual electric horns, but I managed to bolt and rewire everything really tight and neat.

They DO sound louder than any factory horn and their desperate note scares the crap out of any reckless SUV driver trying to cut me off.
The air compressor seems a little weak for the size of the horns, and after reading some comments I agree: These babies deserve a much powerful air compressor (the Wolo 808 heavy duty compressor)

For the price and the sound you get, buy them. If you're not skilled or have the patience for work for two hours under the fender to figure out how you will fit these LONG horns, don't. In a pickup truck or big Detroit cruisemobile they most certainly can provide a more relaxed fit.

For a plus, I think next month I will buy Wolo's more powerful replacemente compressor (model 808) and for the real kicker I'm thinking in how to ADD (instead of just replace) the second compressor alongside the original, so I can get some 35 psi of air pressure, instead of just 12 psi. Most buyers of these horns are already doing this, so if you have the cash, buy 'em both at the same time and please comment on the outcome.

*Wolo Model 417 Long Horn Plastic Dual Trumpet Big Rig Sound Air Horn Kit - 12 Volt *

FIRST OFF...THIS IS LOUD...Every time I honk it everyone around my car jumps. It also has a very distinctive sound. Funny enough, my daughter couldn't find me after her school dance, so on a whim I thought I'd honk my horn and, you guessed it, she found me in 10 seconds. When she got in the car she laughed and commented on how she new that had to be me because no one has a horn that sounds that cool. Now I'd like to add, it's not as loud as the awesome big rig horns, but it's way louder than I expected.
SECOND TO NOTE...IT WASN'T HARD TO INSTALL...It literally took me about 30 minutes. I opened the wheel well to the horn, disconnected the wire connectors, studied the opening and mounted the system, faced the horns down(mainly to avoid water damage, but also set to face towards an opening so the sound isn't muffled much). It was seriously a piece of cake.
LASTLY...There is a very slight delay, but it's so minor I'm not sure that I would have noticed it if another reviewer hadn't mentioned it. If you end up buying this horn, sorry if that last bit of info bugs you, too.
You should check out my pic of my hotrod...I figured for the fantastic price I'd try it and if I didn't like it I'd put my Ooga horn back on. WELL...NO MORE OOGA HORN, okay, I may put it back on, but with a flip-switch. This horn is definitely staying on. I can't believe what a great deal I got on it.

TWO-THUMBS UP...TWO LOUD THUMBS UP, THAT IS!

Go big or shut up.

These horns are pretty loud and they help give my little 1996 Geo Prizm a bit more bark when it comes to alerting other drivers or scolding hooligans on the road. I wouldn't say they're even close to as ferocious as an actual big rig's horn, but for the price, I can't complain.
The installation was pretty easy, though the trumpets are a bit long, so you may have some trouble finding a suitable location to position them. Luckily I was able to tetris them into my compact car's front end.

I've had them in for a bit over a month now and they still work fine through my light usage. I'll update this if they fail later on for whatever reason. Keep in mind that the compressor uses more power than many stock horns (especially in small cars) and you'll want to swap its corresponding fuse with a 30amp one