I put an air horn in our first Fiero. loved it, not that expensive really 30 bucks I think, comes with their own small electric compressor, worked great whenever anyone walked in front of me especially the girls with big hooters.
you can even get ones that play tunes now, just about anything you want from the dukes of hazard to Tchaikovsky's 1812 Overture.
I did put a Buick full size set in our 86 SE we have now. any bone yard set will work.
Technology is great when it works,
and one big pain in the ass when it doesn't
Detroit iron rules all the rest are just toys.