I suggest sending your radio off to
http://garytayman.com/stereo.htm
I've had two radios converted by him and the results are great. Great sound etc.
I've used the Retro Sound speakers a couple times now with poor results. I ended up using the Custom Autosound versions of the dual coil speakers and first thing I noticed was a distinct improvement in sound quality. I can't attest to longevity, as I installed their speakers (in two cars) this summer. The Retro Sound speakers never sounded that good to me and only lasted a couple seasons before failing miserably.