How much horsepower does a 1999 Honda accord coupe have?
According to Honda specs, the 4-cylinder model is rated at 150hp at the flywheel. This translates to approximately 132hp at the wheelbase for a stock vehicle as per dyno tests performed by Import Tuner magazine (can't remember the exact issue number.) A 1999 V6 model is rated by the manufacturer at 200hp (at the flywheel.) I don't know exactly how much that translates to wheelbase power but, by interpolation, it should roughly translate to 176hp.
Mine is a 1999 Accord V6 coupe and I don't think there's a horn fuse. There is a horn relay under the hood in the back left in a black plastic box. On mine there are 3 identical relays (2 for headlights and 1 for the horn). If the 4-cylinder has the same arrangement as the V6 you could switch the relays to see if that was the problem.