Larsalicious

My 04 TSX didn't come with one, how or where do I get a spare key set with a remote transmitter?

mltk53

ebay. or try to get one from the dealer by telling them that it didnt come with one.

SoCaliTrojan

You'll have to buy the remote and key, have the key cut, and then have the dealer (or a locksmith with the right tool) program your immobilizer.

If you're going to do that, you might as well look into getting the switchblade key (do a search for it here)