I have two systems, FAST with dual sensors and the RPM option and a Innovate LM1 with the RPM and LC1 option which converts the LM1 from a single wide ban to a dual sensor. The FAST had one side failed within ten minutes of using it on a engine dyno test FAST repaired it under warrentee and now the RPM feature doesn'r record The FAST system has memory for one recording session and no provisions to store and tranfer that data to any other device. The good news is the Innovate LM1 failed after a lot of use and it was repaired under warrentee and it still works well That system will store multiple sessions as well as let you hook up a laptop and view the session in real time or store the session in the LM1 and transfer that information to the laptop later. The bad thing about the LM1 is that it is a single sensor system, but they do now sell it as a dual wide ban systemm or you can buy the LC1 add on to convert the LM1 to a dual wide ban system I have not hooked up the LC1 into the LM1 yet so I can't offer any experiences with it yet, the LM1 also has room to add up to five sensors for oil temp or any other option you may want When it comes to tuning the AFR I don't think that there is a perfect ratio for all combinations, I use it to learn from, I lean it( part throtttle cruise, idle and WOT individually)) down until it starts to ping and then fatten it up to stop the pinging or surging at part throttle. The weather and fuel, winter mix versus summer mix, out here makes a difference, the fuel will make the car run differenent and read different Ultimately, for racing, the time slip is the final input on my tuning set up on the carb and timing There are other systems availble now that I have no expereinces with so don't be afraid to try them unless you want to go with a proven system