A reputable local shop has commented that the Ultimate can be spotty. They found that it will work perfectly on one car, but on an identical car somehow it won't work well at all. They had that issue with a couple of celicas. Similar cars, modifications, etc., but the ultimate worked perfectly on one car and had all kinds of issues on the other. They finally figured out that the ultimate was too sensitive, it would pick up interference in the wiring harness and the timing would jump all over the place. In a sense it was too sophisticated for it's own good.