I tried to save money and just welded a piece of 2.25 inch exhaust pipe to the original tailpipe, which was still in good condition, when I replaced my uitlaat last week. I noticed however that the original tailpipe was not exactly round so I had to be creative in my welds; I c ut bend notches and bent the pipe to fit. I replaced my old uitlaat with a Flowmaster which was shorter than the factory muffler (therefore the short extension to the tailpipe).
It doesn't solve the rusty pipe issue with the rest of the system, however. A complete replacement with RVS pipes would be best. What I did is only good if you want to save money.