Installed the supertones I ordered in the group deal from Soundmike (thanks man ). I used 16AWG wiring and they're not as loud as I expected, but still loud. Now the horns sound like a good set like they should straight from the factory, not like the crappy stock ones. My 500 MHz is aimed towards the radiator because I couldn't find a 1/2" bolt to install it in the front column. Installing these was a pain because of the tight fit behind the front grille. I'm a small guy, and there was barely enough room to get them installed, and my hands are all scarred. Anyone who plans to do the install might consider removing the front bumper .

I'm going to leave them alone for a few weeks and see if I get any grief for the loudness of the horns. If not, I'll switch to 12AWG wiring and hopefully they'll be even louder.

Here's a good site for the install:

http://www.susquehanna.com/susq/other/horns.htm

I'll take pictures and post a link to them tomorrow. If anyone has questions about how to install them, feel free to PM me. Even with the information I found on the forums, it was still not an easy install.

 

A couple of other items to keep in mind:

I used the gold terminal as the ground, and the silver as the power.
I grounded one horn to the chassis, and the other to the negative post of the battery.
Our horns are 12V switched, not ground switched.
I used about 28ft of wiring for the install (relay is installed in the fuse box on the passenger side of the engine bay).
The stock horn wire is 22AWG.
The bolt on the back of the supertones will not move, you can't take the arm off the horn (unless you're really strong or willing to risk breaking the horn).
Ignore the included instructions about positive or negative push.
I grounded the relay to the chassis.

 

Here are some pics of my install on a 4th gen.

http://imageevent.com/1max2nv/hellasupertone

I ground both horns to the mounting bracket.

 

I was able to loosen the bolt. I wanted to flip the arm 180 degrees so the connectors were on the top of the horn. It is really hard to do...as I was crankin' on the bolt the horn flew out of my hand and went bouncing asross my garage floor!!

Thought I may have broken it, but it works fine. Didn't even scratch the red paint!! (Nissan could learn something here!!) I'm impressed with the build quality of these.

I wired it without the relay, but they're still quite loud. Stand about 10-15 feet in front of your car and have someone honk them...they're pretty directional. They don't seem as loud in the car. I'll add the relay soon...might be a bit louder and won't risk blowing fuses...

 

You're lucky you can remove the grille. On the 5th gen, the grille and bumper are one piece, so it's difficult to get to the area behind the grille. What a mess!

 

I tried to brace the horn against a wooden block and against concrete when I was trying to loosen the bolt. I chipped the wood and the concrete and barely scratched the horn! Steel construction, very durable. I honked the horn standing inside the door and it sounds pretty good, just not piercing or frightening. Still impressive though.

It's a good idea to add the relay. Not very difficult either. Let me know if you need specific information for the install.