Lot of old threads about horns and is good to come up once in awhile too. There are some that have direct replacements installed, some switched to other brands as mentioned, newer hardtops are mounted different, and some people have put them on the side, and at least one went to an an air horn.
For what it is worth, I changed model in the AFI line and aimed them down a bit to drain. I replaced the two horn AFI with the front mount support in July 2002 and it is still working. I had replaced the original model the year prior and it failed in a year. My latest AFI is two horn but I gave up decibels. It doesn't have the front support so I can angle it.
Here is one side view. You can still see the hole in the roof and rubber seal for the front support not used on this model.
We took a ride from Hingham MA to Provincetown last weekend, 55 miles each way for the weekend. Each way about 1/2 to 2/3 of travel was 8 to 12 mph due to head-on serious wave action. Every bit of the boat was thoroughly salted and tossed and turned like being in a washing machine. The horns worked. Virtually every wave went into the windshield or over the cabin top on a 2530.
FYI, I also had taken Thursday off before I knew I was taking the trip and had put Rain-X on the windshield and for most of the trip I didn't even use the wipers!!
When the day this 5 year old set of horns fails I'm going louder again but I will figure out a mount to angle them. This AFI model going on 5 years does not have a stainless steel diaphragm.
Dana