its a product called "dragon fire" or something like that originated in japan. it has a small fuel by pass and spark plug at the end of the muffler. upon a hit of a switch extra fuel will go out the exaust and ignite. i suppose they mix certain stuff to make it different color.
198? 300D ???K - Future DD
1989 300TE 285K - traded in '12
1984 300SD 186K - Sold in 08
1978 300SD 330K - Died in 05