Nitrous Outlet Product Details - EFI Dry Nitrous Systems - GM Systems

this would be a good kit for you.
and like WARLOCK said, the dry shot just puts nitrous into your intake and the MAF sees the extra oxygen and adds the fuel thru the injectors. a wet system adds the nitrous and fuel after the MAF and doesnt rely on the injectors.
the wideband is a gauge that has a sensor in the exhaust to monitor the air/fuel ratio to make sure you arent running too rich or lean