A collection of theories put together comes to this conclusion:
From your pictures, you have a rather high flow exhaust and intake.
In certain situations, your motor and exhaust would be wanting more air than your intakes are allowing to enter.
This is not a problem in and of itself, but this creates negative pressure, or a vacuum, in your air box.
Again, that is not a problem, but your air box has a line that runs to your crank case breather port.
The collection of theories is that the vacuum draws oil from the crank case, thus causing puking.
In my personal observations, I had no oil puking problem with the stock intakes and pipes. I changed those up in several configurations and developed a puking problem. I say this to point out that no more oil was added and no oil change was done after the mods and before the puking development. Therefore, for me, I do not think it was an oil level problem.
My fix was to go to Pep Boy and buy a Spectra small breather filter. I did need to bore out the rubber attachment point on the filter to fit the breather port on the crankcase, but it fit in there just fine and actually looks good. This also let me eliminate the breather line and I plugged the hole for the line in the air box.
I have 0 miles since the fix, but I expect it to fix my problem but only time will tell.