They already have a sticky sponge backing. You snap the lugs off, peel the tape and fix to your car. These are in Maserati bags but are identical in size, finish etc to GTV ones.
Clean your car and use lighter fuel/isopropyl alcohol to get the wax off the paintwork, leave the badges on a radiator to get the adhesive as sticky as possible, and ideally gently curve the badges slightly - gently I said! The GTV flanks are curved a little and all Pininfarina badges are flat but a little bending makes for a better contact.:thumbs: