Have you ever tried installing one? I haven't; but, my research says that it is not easy to get it right unless you do it pretty often. I've found a recommended installer; but, they are in Scottsdale. A friend just had an Evo done by a guy in Tempe that was recommended; but, he had not really done it on a regular basis in the last couple of years. He was not happy with the result. I assume that I would not have the experience necessary to do it myself and be satisfied with it.
Good luck. ( Google it, and you will find some kits. )