Re did the header mockup, got a little more room and made it closer to equal length as I could.. wasn't trying for it, but turned out good. No special spark plug wires required
These plumbing caps work great if u needed to purge a tube.. I dont have that setup, be nice but works good for leak testing... just drill a hole in the middle of the bolt and connect a hose to it. I made one, just need to find it.
Also, if you take it apart and have some BMW n62 valve cover bolts laying around (I'm a BMW Master tech, and just happened to have a few old ones in my tool box), you can take the rubber grommet off, push the bolt out, shorten the sleeve and presto, tight fitting insert that can be pushed into the small disc end so it can then be used to mount/hold a tube to the mockup MDF flange. Just snug the bolt to the flange and test fit till it grips the tube. Wrapping tape around a bolt and washer works too..
