Almost any aftermarket horn would work for a Pajero.

I'm currently running a Stebel Nautilus.

My brother went from stock to Hella, to Stebel, and now he's running Bosch.

My pal is running a Mitsuba unit.

It'll work, it's not rocket science. <img src="/forums/images/graemlins/wink.gif" alt="" />

Ok here's how the local shops do it (please forgive any detail errors, this is just meant to be an overview).

1. Unplug stock wiring from stock horn and set aside. Remove stock horn now.
2. Run new wiring directly from battery's positive terminal
3. Make sure there is an inline fuse that runs with the new wire
4. Wiring from battery goes into appropriate socket on relay (there is a diagram on the relay body)
5. Check original horn wire. Determine which is the 'trigger wire' (the wire that gets activated when you press on the horn button)
6. Tap into this wire and connect to appropriate socket on relay
7. Connect new horn to relay and put on a ground wire
8. Test horn.

So in essence, the OEM wiring's role now is just to trigger the relay.

The relay will trigger the flow of electricity directly from the battery into the horn.

Use the appropriate size wires and connectors.