This was not a pretty merge, not like the other one (Which also wasn't 'gram-worthy rainbow stacked dimes and all, but at least the gaps were reasonably close). I didn't have a lot of space to make this work, and had to do a lot of gap-filling; worse still, I screwed up the order of welding to the point that I ended up having to weld down into the centre of the merge which was not possible with the TIG torch.
What I resorted to was... leaving the welder in TIG mode, with the gas
turned off, and hooking up the electrode holder; and using the TIG
remote so I could light off the welding rod easier, and instantly cut
off the arc without drawing a big arc-trail up the tubing. HF-start
stick welding. 
Also, despite my best efforts, something did spring while I was welding, and the two flanges got closer to eachother; which means it now grips tight around the studs on the head and requires a prying screwdriver to fit. It does still fit, though, and the flanges are pretty well aligned with the head, so I'm not having to draw them up tight with the bolts.
Of course, having figured I was finished with that, I reinstalled it to start planning the next move and discovered that I was way off at the outlet end.
Some hasty shortening work later, and it fits but only just.
This does mean, however, that Phase One is over; and Phase Two can begin.
And oh boy was this bit going to suck. I was hoping I could get both
flexi pipes in where I want them, with minimal additional clearancing
needed, and that I could put the merge together in a reasonable amount
of space so the O2 sensor isn't halfway down the truck.
I welded myself into this corner, I can weld my way back out again...
Unfortunately, I didn't manage to get the pre-merge flexis in so there
is gonna be the risk that the manifolds end up straining something and
maybe cracking, but I did not have the room to make it work. If I were
to do this again, I would just not. (Honestly, if I were asked to make
another manifold for one of these, knowing what I know now, I'd
definitely shorten up the runner length a good ways. A log style
manifold is, in all honesty, just fine for these engines. I just
wanted long runners because it's cool. )
Amazingly, I managed to weld all of this up without causing massive distortion, and the V-band flanges all lined back up again. And that brings the exhaust out here:
And that's the think-y part of Phase Two complete! \o/ I'm going to add a support (with rubber mount), a flexible section, and another V-band; that and the O2 bung will complete it.
Phase 3 will be silencer. Let's see how much I can overcomplicate
that! (I
already have plans here, don't worry~)