The ignition timing/mixture program for the M103 is fairly complex, but I've heard that the resistor is there for certain modes, I think low speed low rpm high load or some such. removing it may cause knock (and may also get you some small amount of power at certain rpm).
I'd leave it alone, MB ain't gonna cheat you out of performance just to make the car slower (drive a C280 for proof).
1972 220D ?? miles
1988 300E 200,012
1987 300D Turbo killed 9/25/07, 275,000 miles
1985 Volvo 740 GLE Turobodiesel 218,000
1972 280 SE 4.5 165, 000 - It runs!