Yesterday I got a greddy turbo timer installed on my 05 EVO RS and later that night my friend told me I had a taillight out, could the installation of the turbo timer have anything to do with this?

 

could have blown a fuse

 

its possible, but not likely if you used a harness

 

If its the right taillight, its probably a blown fuse (assuming its not just a bad bulb) I accidentally shorted something and blew the fuse to the dash lights, turns out the fuse seems to also have the right rear taillight in common..