You are right, a non-cat version was available in 86, but mine has one on it. It also has a smog pump which I think is factory. So it had all the basic emissions stuff on it. What else could have really been done? I think all they did was mess with the timing and general tuning. I was just posting this to find out if there was anything I don't know of, because I am wanting to return my car to exact euro spec.
'86 420SE Euro
904 Midnight Blue, Gray Velour
Dad bought it new, now I own it.
"A Mercedes-Benz is like a fine wine, it only gets better with age."