Suggestion on how to make my car more theft proof?

I drive a 1999 Honda Civic SI and those are thief magnets. Currently I have one of those car alarm that if you open from inside or even from the trunk then the alarm will go off. I also have a steering wheel lock too. I was thinking of getting a car tracker device but you have to pay monthly for those. Detachable steering wheel also known as quick release came in mind but they are expensive and i don't want to carry my steering wheel everywhere i go.

You could invest 400-500$ and get one of those Viper security systems. From what I've read, those are the best security systems… Although it's tough to justify spending that much money to secure a '99 Honda unless you have some extra money to throw around.

Really, your car sounds about as secure as it's gonna be. If someone wants to break your window and swipe your stuff, all that can take less than a minute and there's just not much you can do about it, alarm or not. However, you have the alarm on your car and the steering wheel lock which would make taking your CAR pretty difficult.

Remember to keep your car clutter free and to remove the faceplate from your stereo if you have one.

Sleep in the car with a shotgun. No matter what kind of alarm system you have if they want the car bad enough their going to get it

That sort of alarm may depend on a Voltage Drop sensor. When you arm the alarm it takes a few seconds to register the Voltage in your battery. When you open a door or the boot a light comes on which uses power from the battery. The alarm detects that and sets off the alarm.
I used to go to a breakers yard and get a spare light switch (Spot light if they are not fitted) then remove the Instrument panel and cut into a wire from the ignition system, Wire that through the spare light switch and put it all back together. If you use a different one it is a bit obvious.

Andy C