I have buy my FT 100 two years ago. It work well but the speaker it's too little , the sound quality it'n not good and in the car it's cut the low frequency too.
The solution are two : changing the top of the chassis with a FT 100D case (it has the loudspeaker bigger than the old version) or , if you have no money....!!! , connect a little electolitic condenser to the plug of the speaker.
Remove the top cover and you find on the left part at the center of the radio the BF amplifier unit.
Connect the condenser on the little plug direcly with the same polarity without cutting wires o soldering and the condenser now it's locked from the speaker plug and other plug.
This mods will decreasing a little the audio level and the noise but my transceiver now working better than original.