It has been discussed in other threads that a periodic muffler wash is good for removing soot and carbon deposits from the exhaust pipe of diesel-fed vehicles. The warning was that this should not be performed on a diesel vehicle that has a catalytic converter, such as the new Isuzu Trooper. My question therefore is is it better to stick with diesel vehicles that don't have the cat. converter installed, or does the presence of the converter outweigh the disadvantage of not getting a regular muffler wash?