Nothing but air.
Kinda like moving the PMD on an old 6.5
Anyway, back to topic.....I looked around and couldnt find anything remotely close to a 180* hose-to-hose fitting. But since the two fuel lines to the filter have 90s molded into them, though...wouldnt it be simpler to turn the outlet hose around to face the inlet hose (have to trim the inlet down a bit to match, Id think) and connect them with a 1/2"-1/2" straight hose barb?
Sorry, just working off memory of when I re-installed the lines earlier this year. I may be wrong, and frequently am. If so, ignore.