It would do absolutley nothing to the radio except make it more prone to damage should something go wrong with it. If the radio requires a 2 amp fuse then it is not a good idea to install a 7 amp fuse as it will allow more current to be drawn in the event of a problem. You could install a 40 amp fuse if you wanted too but be prepared to see lots of smoke if anything goes wrong with your radio or installation.As for normal operation all a fuse is is a safety switch in the event of a problem.