Does anybody know where to buy a kill switch or is it easy to install in the fit?

 

Fit has an immobilizer and requires a transponder key, are you afraid someone is going to take your keys and steal the car? Roommate/family issues?

Just wire a switch to the ignition ground and hide the switch somewhere.

 

If you mean a racing style kill switch, you might want to poke around the forums for the 24 hrs of Lemons and/or Chump Car racing series; there's good technical info and supplier recommendations available there if you hunt it down a bit. Wiring isn't rocket science, though there are some things to be careful of to make sure you (a) don't fry your alternator and (b) don't make the switch useless by allowing the alternator to continue to power the ignition. Basically, you need to have someplace for the current generated by the alternator to go even with the kill switch turned off; there are a few ways that can be done.

 

You can use ANY switch you can find at radio shack or pep boys as long as it's 12 volt rated and can carry the amp load depending on what you want to do with it.