I'm sorry to hear that Johnny
. I always thought that the stock alarm system was good.
The only bad thing about it is that I'm pretty certain that opening the hood doesn't trigger the alarm. It sounds to me like it was a pro but not sure. It had to be someone who knew something about an SVX. If they used a glass cutter and then stuck their hand in to open the hood they could easily disconnect the horn to get into the car because then the alarm would be rendered useless.
I hope you get your car back man and find out who's doing it. I actually hope you're in town and you see some random dude getting out of YOUR svx in a parking lot so you can beat the crap out of him.