I put a 125dB horn on with the spade lugs provided and No relay. Haven't had a problem yet, the wire size and contact size appear to handle what little the horn I have uses. Even checked the contacts on the wifes S40 and nothing was pitted.
Here's a pic from Jon's website
http://www.jonline.org/savage/Tips___How-to_s/Tips___Tricks/tips___tricks.htmlScroll down a bit to see the horn, I got the same thing at Autozone for $20, one of the notes (low or high, I don't remember) didn't fit right. The other was perfect. It just barely touches a turn signal, but you can change that very easily.
VHFKID