looks good enough to be a final system, I would just put some more time into making smooth radiused curves on the pipe coming from the front manifold, where they seem to make two 45 degree sharp turns. Not too hard to take two pre-made curved pieces and replace just that section. Did you manage to do slip joints and then weld? If it's butt-joints without internal overlapping, you may not want to grind the welds flat. You could slip a piece of smaller pipe inside the two, so you have more to weld on, get deeper penetrated welds and stronger structural support all out of sight. Then you can grind the welds flat. I understand this setup was not made/meant to be permanent, but it seems like it easily could be with just a little extra work, if any at all. Looks nice.
