Man, too much time on your hands. I used these from Amazon, can't beat the price. https://www.amazon.com/dp/B088NHBDSD/?tag=atomicindus08-20
You might think it was a lot of work, but the truth is it wasn't. It was plain carbon tube, the welds were all ground. Sure, I ground the tops because they weren't done to look pretty. Nope... just to fuse the pipe. But it was also a speed thing. Set the power source, track a straight line and it lay down penetrating caterpillars. You'll notice all the parts were similar, chop, chop chop. Weld and grind. Easy peezie. Like an ***embly line. Duals done in a day. And the tubing, 3 -10' sticks of 16ga. x 2 1/2", Around $100. Bought through Napa, get your best deal right? I think I beat the price. But to each his own. I choose the 2.5 tube not for any reason other than that was the inlet of the mufflers, a OEM factory quiet rumbling set of takeoffs exchanged out for a "free flowing and excessively loud" set to annoy everyone else and buddy was getting rid of them. Just how I roll. Right place right time. Don't think I'm against the kit thing, I'm not. Matter of fact, I have a set that I picked up, again, right place right time. I'll one day sell it off now. Plastic tote special.
We didn’t opt to tear up the bathroom floor or excavate to get to that section, which would have been ANOTHER $25K. We’re counting on that outliving us.