The Bose speaker system is 2ohms. However the front left and right dash speakers are 4ohm each wired parallel to the 4 ohm left and right door speakers to create a 2ohm load for the front left and right channels. The center channel is 2 ohm, i believe. And the rear door and rear pillar speakers are wired the same as the front channel speakers to create a 2 ohm load for the left and right rear channels. I would use a matching 2ohm speaker component set front and rear to get a better sound using the stock Bose amp and use a matching a coax speaker for the center channel. However, if you are going to use a aftermarker amp then I would use 4 ohm component speakers because they are usually less expensive and have more brand choices. P.S. Do not add 2ohm door speakers to the 4 ohm Bose dash or pillar speakers or vise versa while using the Bose amp, it will create a 1.2 ohm load to the Bose amp, which may shorten the life of the Bose amp due to the higher current load.