Greg is right on the money.

The new 91 surpass' have that line return to the intake manafold (Note: this type MUST use a pressure line from the muffler to tank)

The previous versions (With the nipple on bottom) do not NEED to use muffler pressure, and as others have mentioned, you can just put a piece of fuel line on the nipple and run it outside the cowl... or you can do nothing with it if you don't mind getting some black oily stuff on the inside of your cowl.