Aftermarket alarms, car starters, audio, lighting
Alarm Brands/Starter Brands:
Viper, Compustar, Clifford, DEI, etc. Honestly the list goes ON forever. But personally I am partial to the first two. Some of them have GPS tracking attachments that hook up to your cellphone. You can see where your car is, start it, lock the doors, unlock, roll down windows = from pretty much anywhere in the world as long as you have cell service. Why buy aftermarket alarms? Thats pretty self explanatory. Theft prevention, Convenience = some of them are hooked up to car starters, these alarms usually have much better range so finding your car or locking and unlocking has a bigger range. Some let you roll down the windows from afar..
Audio:
I'll be honest I'm not a big audio guy so many someone else can chime in here. Alpine, JL, Pioneer, Kenwood, Rockford, Clarion, Sony, etc. Such a huge market... I don't have the time or the interest to keep up with the changing market but I know some are very passionate about this topic.
Lighting:
LED INTERIOR LIGHTING! LED REVERSE LIGHTS! HID REVERSE LIGHTS?! UPGRADED XENON BULBS! UPGRADED PROJECTORS! CLEAR LENSES! List goes on.
retrofitsource.com
vleds.com/