realize that the scangauge came out several years before the ultra gauge. the people that did the scangauge had to do it all themselves where as the ultragauge people had a lot to build from. R+D is expensive. you also have the added feature of removing the cord from the scangauge so you can go from car to car and not have to have the wire dangling around when you do install it.
I can say that the ultragauge is a nice setup, it still has its disadvantages. I think it is a personal preference whether they outweigh the price difference as I am very partial to the scangauge. two guys that I work with have ultragauges so I have played with them.
for a long time, scangauge was pretty much the only way to go for OBD-II (not because it was the best, but because there was nothing else)
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