Size shouldnt be much of an issue. Just use a filler for the space the cobra goes, and then attach the new emblem when its flush and it should look fairly clean. Go with the smaller one as the 5x 5 would probably look retarded and way too big.
Just use google for the custom decklid emblem as there are plenty of places that will do it but it usually isnt cheap for them to cut one or only a couple custom emblems alone.
Just use google for the custom decklid emblem as there are plenty of places that will do it but it usually isnt cheap for them to cut one or only a couple custom emblems alone.