Richard, the Interceptor is 58 watt siren as well is the Director. Since they are both transistor driven sirens, if you tried to reduce the out-put power by placing a choke or resistor in line, you most likely blow the transistors and that’s a very expensive oops...
If you think that’s loud, you should try a PA-200, which is true 100 watt siren and mine seems to blow all others (except mechanicals) out of the water in parades and car shows.
Another way to dampen the sound is to get 2 extra re-entry cones and fill them with something like Silicone. Then when you want to runs the siren with lower volume for like a show, you would unscrew the clear tubes and screw on the dampened ones…. I have a nose cone like that on my bench for siren testing….
Good luck!