Diesels smoked up until 1985. The last year Mercedes used the OM 617-952 engines in cars intended for the US market. No DPF, catalyst, or urea injection. The EGR could be disabled by plugging one vacuum hose. No ECU or CEL Big Brother devices to keep you from doing that either. Not terribly hard to tune up for crazy power and the engines are strong enough to deal with being turned up just fine. Mine has the fuel delivery on the injection pump turned up a little, turbo is set to 14 PSI, and the EGR is repaired. You are not supposed to feed soot back into a turbo.
They who can give up essential liberty to obtain a little temporary safety, deserve neither liberty nor safety.
Benjamin Franklin 1775
Sell not virtue to purchase wealth, nor Liberty to purchase power.
Benjamin Franklin Poor Richard's Almanac1738