well if you don't have RPM capabilities, its a little harder to judge the afr at a certain RPM. You "can" do it by watching the tach & afr meter while driving, but if your car has any balls whatsoever, that becomes a challenge!
The unit will record up to 44 minutes of data. If you want to use the record function and download it to the computer to view what's going on, the RPM device allows you to make sense of your data, as you can see what the AFR is throughout the rpm range.
I've got the LM1, and really like it. It's best to be decent with a computer if studying all the results in graphs and all.
I am going to order one next week as well and was wondering about placing the o2 sensor in the middle of the X-pipe instead of on one side of a header tube? Wouldn't the X-pipe be a better location for an airflow reading instead of buying two bungs and placing one on each header in order to get a reading from both sides.
The O2 sensors are self heated, so they don't have to be placed close to the head. They can go in the tailpipes for that matter! Mine are in the exhaust pipes shortly after the collector.
One of the best things about the Innovate prodct is their forum, where people can go to ask and answer questions about their product and tuning. The owner of the company even hangs out there to steer people in the right direction!
I've got the aux-box for mine as well. The only functions I've used so far are the rpm and vacuum. The vacuum gives a sense of the throttle position. When all the data is downloaded, there will be graphs of rpm and vacuum against the AFR.
However, this unit is around $250. The rpm converter is only $99, and is really all you need unless you plan to test some turbo/supercharged vehicles.
I bought two extra bungs, one for another car and an extra for whenever. Who has the best deal on feedback transducers for electric gauges. I already have electric NOS pressure and Fuel pressure with the 0-5 vt feedback transducers, but want to look into other feedback alternatives like Vac, water temp, voltage etc..