First, its true, there is no catalytic converter, most diesels don't have them, because the sulfur in diesel fuel would destroy them anyway.

Engines don't really need backpressure, but even if they did, the turbo provides more than enough.

MB diesels are breathing more air than they need as it is, so bigger intakes and bigger pipes don't make much of a difference, if any difference at all. You shouldn't put on a straight pipe and expect to get an increase in mileage. It'll just get louder.

To improve mileage, make sure your filters are good, there are no fuel leaks, either at the tank, or around the injectors, or at the primer pump, make sure the valves have been adjusted, and that your injection pump is properly timed. A properly functioning turbo will also help your mileage, so check to make sure its producing enough boost.

Anyway, these things should give you something to do for now. Enjoy your car!

peace,
sam

__________________
"That f***in' biodiesel is makin' me hungry."

1982 300TD Astral Silver w/ 250k (BIO BNZ)
2001 Aprilia SR50 Corsa Red w/ 5.5k (>100 MPG)