I have a dashdaq with the zeitronix unit and a wideband AFR. Its a good combo. However, according to some reading I did on the web after I bought it there are more accurate AFR's than the zeitronix, but as with everything better costs more. I think MrPhotoman posted a link to an AFR wideband shootout that was pretty informative.

Anyway, the dashdaq is handy, as it will log any of the OBDII signals, as well as inputs from other popular sensors/loggers like the zeitronix. Conveniently, you use an SD memory card to hold the logs, and you just pop it out of the dashdaq and into a PC to read the files.

Unfortunately, the dashdaq doesn't come with any software that is good for reviewing the log files. (You'd think for $500 that they would include something like that!) So you're pretty much at the mercy of your own Microsoft Excel skills. There's a free program that you can download that will read in the logs, but it's not very user friendly, and I find its easier to just use Excel.

Lastly, one other thing I don't like about it is that since you're reading most of your sensor data from the OBDII port, you're stuck with the OBDII port's update speed. When you're logging several sensors (such as MAP, RPM, Throttle Pos, Timing, MPH, etc.) there's a marked delay between updates of each sensor. This isn't the dashdaq's fault, because the OBDII port only supports so many updates per second. So if you need very precise and immediately up to date signals to compare with each other, you may want to invest in additional sensors to reduce the load on the OBDII port. The fewer items you log from the OBDII port the more frequent the updates for each OBDII-based sensor.

I'm considering adding the zeitronix boost sensor so that it's one less OBDII-based readout and I'd get faster updates on my other data. But it's about $100 for the boost sensor...