We tested the Seelevel system a while back. Way more accurate...but the electronics were a little bit finicky for our taste. When they worked they worked well.
You might also look at the Horst Miracle Probe. There is a video on the site that shows why they read incorrectly and how this probe is supposed to solve that problem. We have tested these as well and seem to get good results.
PLEASE do not send questions via Private Message, my inbox fills up too quickly. Post questions in the forum as a new thread so that other users can benefit from the answers. Use Private Messages for sensitive information only (VIN, Contact info or things you do not want the public to see).