I've been using a tag for over 10 years and like it a lot. If you enter good info it will give you good predictions. I am a dealer for computech (for a about a year and a half) and have sold a few of their handhelds. The guys that bought them like them. I've noticed the pro teams use a lot of computech stuff so it's gotta be good. If I were going to buy one now it would be a computech. The handhelds are accurate and affordable, of course the trailer mounted remote ones are better but much more expensive.
http://computechracing.com/Product_G...-portable.html