OEM vs. Aftermarket Alarm for 328i... Opinions?

Okay, I've been looking into this and researching options for quite some time now, browsing various forums, and I don't seem to have a very clear idea of what would be a better option for my '07 328i regarding an alarm, so I decided to consult you fellow Bimmerfesters, since you've been so helpful in the past . Because my car is '07, it came with the prewiring for the alarm, and lately with the surplus of vehicle break-ins and thefts in my area I've been highly considering getting an alarm, for either a legitimate theft deterrent or just a lights and sirens show to at least "scare off" potential thieves/vandals.

In the past, I've read that alarms are not really a great theft deterrent at all based on people's experiences, but that the little flashing light indicating that an alarm was active was enough to keep people away. Anyway... I guess my question is - regardless of effectiveness or ineffectiveness of having the alarm - which is the better option, OEM or aftermarket? Both will cost around the same to purchase and install, I've found, so cost is not the issue so much as my concern that an aftermarket alarm may screw with the car's computer/electronics (is this even true, or a myth?). There was one particular brand of aftermarket alarm I looked a bit further into, called Viper - seemed to have all the bells and whistles (remote start, horn, flashing lights, etc). Has anyone heard of it or had any experience with the brand? Any advice or opinions would be GREATLY appreciated.

On a totally off-topic note, below is a photo that I took this afternoon of my BMW in the snow.

Factory alarm. It is an easy diy and have the dealer, or a good Indy, code the car for it. Available at www.getbmwparts.com as well as other places. Factory alarm has an interior motion sensor and a tilt sensor.

I like the OEM unit because it enables the clown nose to blink. Visible deterrent against casual theft attempts.

I'm also 100% in the OE BMW camp. It plugs right in and works beautifully. I installed my own in my '09 X3 and had my indie code it. Took 20 minutes total and only charged me $30.00.

Plus your car is already completely wired for it. Some newer models aren't. You will get the deterent effect immediately on install even if DIY. The clown nose on your mirror will blink. It will blink and error code, but thieves don't know that. Once you get it coded (dealer charged me $100, indy should be less) it will blink the correct pattern and functions as designed. It works great and I have never had a false alarm. If it goes off, someone is tampering with your car or you locked the dog in there. Learned that from experience.

Thanks for all of your input, as I see nothing negative about the factory alarm thus far, it seems to be the clear winner in this situation - especially being an easy DIY, which is a BIG selling point for me. I'll give it a go, probably within the next couple of weeks or so.

Originally Posted by cruisingbimmer

Thanks for all of your input, as I see nothing negative about the factory alarm thus far, it seems to be the clear winner in this situation - especially being an easy DIY, which is a BIG selling point for me. I'll give it a go, probably within the next couple of weeks or so.

If you buy the OEM alarm, the installation instructions with pictures is actually in the box.