daeman
+1y
If your not confident welding a new section in, get a bunch of spare/scrap exhaust pipe and practice on that till your comfortable, exhaust tube is pretty easy to blow holes in and the like if your not careful. Especially used exhaust tube.
Otherwise, like baha said, you can use pipe and clamps. That said, because your trying to extend it, I'd recommend using tube that will slide over the existing tube fairly snugly and cut 4-6 one inch long slits running longways in each end of the tube where its to overlap, so the clamp can crush it down onto the smaller tube, also use mani seal, or some other high temp sealant on your joints prior to assembly. Should work pretty well if done right.