usually sponsored members are more likely to have decals (as part of their contract). there was a guy who was doing lighting work at my job for a while from Alabama and had a nice system (loud) and had a big Diamond Audio decal on his back window (suv). at least he had nice equipment.
depending on where you're at, it may not attract attention or no one will bother with it. but in the ghetto or rough cities, it's advertisement. but hey, what's the harm in showing off your pride? that's why i have an Incriminator Audio team shirt. do what YOU want to do and not let other ppl persuade your decision. personally, i won't do it unless i'm sponsored (which'll never happen).
oh and i'd only put stickers of companies that no one knows about (like Fi car audio, etc) that the general thief would think nothing of.
or kinetik cuz no one really knows about them since they're batteries.