I have a Custom Auto Sound digital system that works great in the 67 Camaro. None made for the 69 Firebird dash yet from them, so I went with Secret Audio. Installing the dash speaker and 2 tweeters on the pillars helped out alot in the vert. Got the kick panels with speakers and did not put any speakers in the back. You can hear it just fine standing on the side of the road when we go by and it is only at 1/2 volume.