Anyone installed the hella supertone horns?

Yes, see the linked thread in my signature below.

SCH-I535

 

These are pretty much a straight swap (with just a little finesse). Easy to do, but the push pins holding the cowl cover on are useless once pulled out.

 

They don't look much different than the one pictured in post #3 above.

SCH-I535

 

Same tones as the PIAA horns above, but with smaller trumpets and they include a relay. They look like plastic. The PIAA are metal and bolt right in with no relay needed. But they should fit OK, there's a lot of room in there.

 

Not sure why rdgrimes said,"push pins holding the cowl cover on are useless once pulled out.", because I reuse mine.
I have to enlarge the holes on the PIAA brackets in order to use the factory bolts though. It took less than 15 minutes with proper tools.

Note for the push pin: first you have to pry up the center pin and pull it up until it stops which is about 1/4", then you can pull the whole pin out.

 

These look similar to the FIAMM 74100 El Grande twin horns I installed. If so, very simple. See my installation review on page 2 of this sub forum which gives step-by-step instructions - which should apply to your installation. The part of my post addressing the horn replacement is #3. The first two are on door moldings and door edge guards.

 

Installed a set of these, pulled the pins out and installed them from the top. There is some sharp edges on the metal behind the bumper cover. so be careful, I had a few scratches on my arms after the job was finished. I didn't have to use the relay that is included, I don't blow the horn for long periods, even though some idiots need it.

2 Piece 12 Volt Electric Horn Set