For what its worth, ive learned thru experience that pretty much any and all air intake mods dont do anything. Piping really means nothing honestly. The only thing that makes sense for piping is that the less bends in the piping the better air flow you get. But thats about it.
What ive learned from having 5 performance mustangs and my Lightning, is that an open filter is about all you need. The stock intake systems are fine, its just the air "box" thats restrictive. Swap that out and you're good to go.
I did the Gotts-Mod, but it did nothing for me until I swapped in a K&N filter.
My mustang with a homemade ram air set up back when I was running it naturally aspirated gained an average 1.5 mph in the 1/4. So this was about a 15 hp gain. Now this was with my headlight removed and a straight shot into the mass air sensor (no filter) as compared to my stock air box with K&N installed. Consider that the car was trapping at speeds in excess of 112mph so the ram air was much more effective. So I tend to agree with Spartacus and believe that any gains you get will be minimal.
Once you remove the restrictive snorkle and do the gotts mod....I really don't think you will see any measureable gain with any ram air set up.