My rear axle is a 3.23 sure-grip. That comment was the first time I drove it with the fitech. It was an obvious improvement over the edelbrock right out of the box. The rear tires are 275-45r18. I picked them so the speedo wouldn't change. Nearly same diameter as 225-75R15's. The fuel ratio is programmable at several points in the power band. Several items I've read on the net recommend around 14.7 at idle because it's the theoretical ideal. A couple sites mention going higher causes NOx emissions if you don't have a catalytic converter. Wide open throttle, etc is a bit of trial an error but can be done with the controller while driving. Pull over and stop first... Haven't tried it yet but having the computer control the spark also allows you to adjust timing from the driver's seat too. Since the fitech knows throttle position, manifold vacuum, etc it can change the ratio based on driving habits. Haven't driven it a lot yet, still working on getting the brakes to lock up when I stomp on the pedal. More important to be able to stop than set land speed records. You can also use a cell phone cable and connect it to a PC and get a lot more data/control out of the unit. I would like to put it on a dyno and adjust for peak performance when I get the time.
