Hey Tony- I think that was because of the gasser requirement of having backpressure. Diesels need to get rid of the stuff as soon as it exits the Turbo, since there is no further use for it. My '96 had the exhaust infront of the rear wheel, but I didn't like the NOISE, and especially the soot on the rear wheel/quarter panel. With the cleaner '03, the soot shouldn't be as much the problem, but noise will be there. Looked really good but wasn't worth the effort to keep the truck clean. My advice- go for it! You can always change it back later.
Greg