I have killswitches and shaved doors
Alarms can be beat man.. Killswitches are cheape and alot more likely to have your car there in the morning. I have one to my fuel pump I use all the time and one hidden DEEP thats for the ecu, but i only use that when im leaving the supra for a while. And the shaved doors do ALOT for security, along with (imo) look pretty sexy.. and you gotta realize that most theives dont want to attract the amount of attention involved with breaking your windows..
The ravelcos are a good investment if you have the skills to install it, theyre like $100 on ebay.. But I use these little Hella killswitches:
http://www.summitracing.com/parts/HLA-002843011/ theyre awesome, because they have a removeable key, and the plastic base is discreet and relatively small..
and just a tip if you have a manual, wire it to your killswitch, wiring it to your ignition, people can still push start that bitch