I run the #4 tube from the collector to back alongside the #2 tube. I do not connect it to the flange at this time. The reason for running the #4 tube back to there is so that I know where to locate the upper bend in the #3 tube to go over it.

I make the collector ends to the #6 and #7 tubes so that I can see where the #3 tube has to be routed to clear them. Remember the LH cyl bank will be the upper set of tubes.

I then finish the #3 tube

Lastly for this side I run the #4 tube the rest of the way to the flange.
