I know I'm prolly pushing my luck but I've had a system in each of my 2 Suv's, EX and my old Isuzu Trooper (R.I.P).
Anyway, I never had any problems with anyone doing anything to my car cause of it. Sure it doesn't look awesome. But it's a box I built with 4 12" subs in it, and an MMats amp sitting on top of it. With a Pioneer 9300 Deck in the dash. Thing that's weird too, is that I've had alarms in both of my SUV's and for some reason neither of them ever worked. One in my EX now, goes off but the siren doesnt' work, it's all hooked up and stuff, think I just need to get a new/better alarm anyway.
BTW I'm 19, and have had these cars all the way through highschool and drove them every single day, everyone at my Highschool new I had my system, I've never parked my SUV's in a garage, and never ever had a problem.
I'm a little less worried about people trying to steal my stuff now that It's lifted cause well you can't really see into the EX that good, but, usually if someone has a nice truck, there is usually some goodies inside. So it's prolly even more prone to getting broken into now.
Prolly should really fix that alarm soon!!!
*Knocks on Wood*