I know this has been done before, but I thought I would show off my latest handy work.
I finished one last night and took the car out for a drive... and didn't notice much of a difference. I will go for another drive this evening. If these aren't loud enough for me I will sell these and buy some supercups!
Thank you Rennlist for the inspiration.

 

Here's what I did, very similar. My impression was that it was slightly more free flowing, and slightly louder, but not a lot. You can click on the link in my signature to see the write-up. My next step was to completely gut the next set of mufflers. They took a few months to get "seasoned", and had a bit of resonance at first, but I like them a lot better now... deep rich tone, free flowing and the resonance is now gone!

 

What welding process did you guys use? Is the body stainless?

 

I mig welded the interior parts since they seemed to be mild steel, then I TIG welded the exterior skin back togther. I also added a few plug welds to support the center baffle section and to ensure it won't rattle.
I used a combination of a sawzall and a 4.5" grinder with a cutoff wheel to dissect the muffler.
You could MIG the whole thing. If I were going to do a lot of these I wouldn't waste my time TIG welding them again. Sure it looks prettier, but whose going to see it?
Now that I got them both on, the car is louder at idle with a deeper sound and a little louder at high rpm. Not quite what I was looking for though.... I think I need some supercups... or to bypass the cats...

 

 

I'm saving my first version for when I can finally afford a set of Chris' X-pipe w/ 100 cell sport cats too!