[LS short box]

So I've built a number of exhaust systems for my hot rods. I order a box of bends from Summit. I don't care for glass packs. Way too noisy. I like turbo mufflers. They cut down the sound and are cheap.
So if you are starting with 2" exhaust tubing figure out where the new mufflers are going to go. Get a piece of exhaust tubing (2) long enough to fit inside the inlet of the new muffler and over lap the current exhaust tubing by about 2 inches. Then take those pieces of exhaust tubing to the local muffler shop and have them expand one end of the tubing just enough to slip over the existing tubing. Should cost almost nothing.
Then after expanding slit the new upstream tubing (4 slits) so using a single band clamp will tighten down over the top of existing exhaust tubing.
Do the slit thing to the inlet to the muffler so the single band clamp will tighten on the new tubing.
When assembling use a bit of muffler cement for a great seal. No welding required.
Good luck.