2010 Sirius Kit - will previous year kits work??
 

I just picked up a 2010 Mazda 3s and looked into the Sirius kit. After I picked myself up off the ground after being told the kit was 500 i started looking online. I haven't found any info letting me know if the kits for previous years will work or if there is a non-oem kit that may be cheaper.

If anyone can assist I'd appreciate it. Thanks!