Heck, I'm not even certain where I got mine, been a few years! Fairly certain it would have come from Geno's though. I could just barely notice a difference in the sound even though it is all straight through. The cat......somehow.....didn't get put back on, not sure how that happened! If you have to leave the cat in where you live, it requires some fabrication. That's a pain, but I did go ahead and do it in case it just has to happen one day. If I recall, the cat had 3" inlet and outlet, so you had to put the 4" adapters on it. I welded mine and then made sure of the fit before benching it.
I think I got the stainless from Geno's, it did not stay shiny more than a year.
I think this forum was the first place I heard about the band clamps. I went to NAPA and got them for the truck. They are THE best no doubt. I either drive my truck, or my 91 Volvo, and I use the band clamps on both, sure makes your life easier, and a better installation as well. You have to give NAPA, at least around here, a few days notice if you want 4" band clamps though!
Good luck, I'm sure you will be happy with either system you go with, all these folks seem to be on top of their game nowadays.
George