Still waiting on the kit to ship. They said this week or next week, but I am not holding my breath, nor do I think it'll come all at the same time.
In the meantime, I had converted my MIG welder to work with an aluminum spool gun, so I could weld thick aluminum, which I used to weld the bungs on my valve cover and on the PCV port. I have a TIG welder, but I had purchased the last TIG welder off the shelf in such a rush that I didn't see it was DC only, so I sold it yesterday and bought a never opened, used TIG welder in such a way that it is basically like I bought this new TIG welder at a $80 discount, so everything worked out. I tried my hand at TIG welding, and it went rough enough that I will practice some before I tackle welding the IC pipes. I am not going for beautiful welds. I am going for that home-built, functional look. I planned to sleeve the pipes all along because I don't want any cracks or failures. I'm not a fan of butt welds on thin gauge tubing, but it will also make welding the thin-walled IC pipes and downpipe easier whether I use the TIG or MIG welder without worrying about blowing through the pipe.
What do I mean by sleeving the pipes? Well, one way is to use a tool to stretch the end of one pipe, so it slides over the top of the other end. This is sometimes called a slip-tip or slip-on style exhaust. My Ducati utilizes this with a double sleeve that the other end slides into that helps to reduce any leaks, and then it is retained with a spring. This isn't what I plan to do. I plan to use a weld sleeve like the pictures below, but of my own creation because why not, and these aren't available anymore. I plan to just cut an inch or so of pipe and finish the edges nice, and then I will just cut out enough of the circumference, so I can constrict the sleeve inside the end of the pipe. This will marginally reduce the inside radius and disrupt laminar flow inconsequentially, but it will guarantee a strong seem.
I also found a nice product on Vibrant's website for a 3'' to 2.5'' transition of a single side to their HD clamps, which perfectly fits my Aliexpress clamps and was reasonably cheap--nice surprise. It means I save some space and have one less thing to weld when I build the IC section where the 2.5'' pipe transitions to the 3'' inlet on the FMIC.