Quoted from jibmums:
In addition to the speech, all the sound effects are pure Firepower. There don't seem to be any specific Firepower II sound effects, are they disabled?
I'm not really sure. My Roms say Firepower II on them on the sound board, but they are just recycled Williams sounds ( like Firepower, Defender, Joust, Robotron, etc.) that all the games of that era had.
One thing I find , and I don't know if this will make sense. With the speech now, it makes the fame "feel" older. When I first got it it didn't feel like a game from 1983 to me. It plays fast and while it had the 80's sounds, it felt to me like a newer machine. The speech really dates the game. Not necessarily a bad thing, just an odd observation on my part.
I still like it though.