Permission to publish this article is provided generously by Robin Sun at www.p-car.com. Be sure to visit his site for loads of 993 info!
This kit replaces the small disk-like horns with the older style trumpet horns. It is a relatively simple installation.
1 Trumpet Horn Kit (I got mine from Carnewal.com)
4 Wide female solderless connectors (wide enough to mate with the horn connectors)
4 Socket pins (came from wire wrap breadboard kit) small enough to fit inside of the power connector. See the pins on the old horns once you?re removed them.
18 gauge wire
Heat shrink tubing (to fit 18 gauge wire)
Phillips head screwdriver
Soldering iron and solder
Crimping tool (for solderless connectors)
19mm socket for removing the passenger side front wheel
Wheel lock key.
The horn is located under the passenger side front fender. Follow the instructions in the How to remove the front bumper cover DIY for removing the front fender liner to get access to the installation area. You do not need to remove the front bumper cover for this installation. Note: Remember to loosen the wheel lug nuts before raising the car (I never remember?)
Looking against the body wall, you will see 2 rubber/steel clamps that hold the oil lines and wiring in place. The new bracket will be mounted to the same studs and will replace the rubber/steel clamps. Holes in the new bracket match up with the existing studs.
The old horns can be seen at the top of the following picture (silver cap, black bottom disks). The bells of the new horns will roughly end up where the old horns are located, above the oil cooler.
Unbolt (10mm) the two existing horns and disconnect the power connectors. There?s a little clip that you need to push down on to release the connector, then just pull out. I was not able to find a matching connector so I made up a set of adapter wires so I wouldn?t have to cut the existing connecter off in case I ever wanted to return to the old horns.
Cut 4 lengths of 18 gauge wire, preferably 2 each of different colors, about 6 inches long. Attach the female solderless connectors to one end of each. Solder the pins to the other ends and secure it with the shrink wrap tubing. Leave about 1/4? to 3/8? of the pin exposed (to insert into the power connector).
Next, remove the 2 rubber/steel clamps using a 10mm socket and install the new bracket as shown in the picture. The rear two holes should be used to prevent interference with the fender liner. The wiring will be held in place by the U-shaped portion of the bracket. Note: The oil lines do not line up with the part of the bracket that is meant for them. I used a large tie wrap to secure them, even though it probably was not necessary.
Mount the horns to the bracket. The longer one on the inside mounting point. Use the original nuts and shake resistant washers to mount them. The shake resistant washer is installed on the front side of the bracket while the nut is installed on the back. Do not tighten the nuts completely. Leave enough slack so that you can easily turn the horns. I pointed the power terminals towards the bottom for ease of access initially but turned them towards the body to keep the wiring off of the fender liner.
I did not modify the original bracket even tough it is slightly in the way. To prevent rattling I mounted some automotive weather strip to the backside of the inner arm (near the long horn) and a small strip to the top of the outer arm (inside the short horn bell!). If the horns should move, they won?t make contact with metal and rattle.
Now make the electrical connections. I connected the left connector on the horn to the Pin 1 hole in the power socket (socket is marked) and the other to Pin 2. I have no idea of this is correct, but it worked fine.
To protect the wiring, I turned both horns such that the connectors faced the body of the car and not the fender liner. I then used a tie wrap to secure the excess wiring to the shorter horn. Hopefully, this will prevent rattling. I also wrapped the power connector with electrical tape, securing the horn wiring to it. I used enough to ensure that no water should be able to get in there.
To test the horn, put the key in the ignition and turn on the accessories (or start the car). Test the horn. If all goes well, you can now reinstall your fender liner and wheel. Hand tighten the lug nuts while the car is still on the stands. Note: Don?t forget to fully tighten the lug nuts after you lower the car (I always forget and almost drive off with them not torqued properly?).