Ahh I'm stupid...it is heater hose, I looked at it last night. I forgot which side I was thinking about too, because it's 1/2" on the driver's side.
I'll pick up some of that PCV hose from the parts store and replumb it...
2005 Mustang GT Premium
C&L Racer, 93R Tune, SR UDP's, JBA ceramic LT's & catted shorty H, Magnaflow resonators, Hooker Aerochambers, Hurst Billet/Plus, "P" springs Spohn reloc brackets/lowers, J&M AL panhard bar, DIY brace, smoked markers/tail lights