dude, talking of FM mods I built one from scratch including capacitance/inductance in early 80's when kenya electronics on moi avenue had an RS catalogue. the transistors were expensive then. The neighbour who would not turn down the volume on his Fm radio in the night got a taste of a square wave modulation centered on his favourite FM frequency! lol! ;-)
Reminds me of the vehicle USB MP3 player (with the FM modulator), interesting how everyone around the device(in traffic) is forced to
listen to the user's playlist, it gives all the interference 12V can give.