[WestCoastSVX]

Was your car originally US or Canadian?

If you actually have the button marked "security" (is it one of the square buttons in a row on the left hand side of dash below the gauges?), my understanding is the factory security system is installed. I thought cars without would have a blank "dummy" switch cover there. Does the red LED light flash on the button?

Going to a bigger diameter wheel size is no problem (I have 18", I think a few 19" or even 20" are out there). You just downsize the tire sidewall to keep the diameter the same. I run 40 series tires with 18's vs. 50 series on 16's. The sidewall is about half the height, but overall diameter from tread to tread is only off by a fraction of an inch, not even enough to affect the speedometer much less cause fit issues. And lower sidewall = handling improvement. Where you have to be careful is offset of the wheels, too much off stock and you are going to rub fenders no matter what size you go with, even 16's could rub if the offset was really off. The high offset, combined with the bolt pattern, used to make it really hard to find aftermarket wheels that fit the SVX. The last couple years a lot more have materialized though, and now there are even a handful of stock wheels from other cars that look great too.