Turtleback - purpose of two tubes

[ward00]

Now that I have found a turtleback for my IDF's, I'm wondering what the two tubes (no, I'm not talking about the air intakes) that each have an external end and an internal end in the vicinity off the inlet to each IDF were originally used for? I'm sure they weren't used for that purpose, but rather than plugging them off, I feeling tempted to use them to inject some NOS.

[grrrdot]

So not exactly sure but I'll guess its part of the breather system.
On the underside my turtleback is one big nipple for the crankcase vent line that comes off the engine block and two smaller nipples for the vacuum lines that come off the 15/13 IDFs.
Inside the air filter is a housing of sorts that directs all that oil vapor into the carbs.

-G

[rebar1111]

That's how I used mine on 40IDF 13/15. It works.