Had my own welded up using a 3"-4" reducer, a couple 4" 90's, some 4" pipe, and about 2" of the original 3" downpipe (for the turbo flange). Of course 'da house' is running a different exhaust manifold than you guys' trucks, so it more or less had to be a 'made to order' deal.
Now, if only I could get that guy down in Ashland to weld me on one of those cool heat shields of his...