no, just turn the car off and let it sit for a bit. it sits about a half inch above the fuel rail, so the pressure would have to be great, and if the pump, injectors and everything isnt going, no fuel should be moving. but if you want, just uncap it slowly to let some of the air out if there is any in there.
oh, and if you have some Teflon tape, wrap the AN fitting with it to get a tight seal b/w the adaptor and the fuel rail. you dont want to be leaking (wasting) any fuel.
**I have sigs turned off, so if you're asking for advice based on your mods, I can't see them**