[david-b]

The SAFC will not fix your downshifting problem. Yeah, you can tune it for more gas at specific rpms, but with an auto it's not going to help it out. It'll downshift, dump the extra fuel in, and sit there burning it with no gains. If you lighten up the car (weight reduction, pulleys...) it'll help out a lot. Also, upgrading the ignition will also help. Better spark plus better transporting of power to the plugs (plugs, coil pack, wires) will help too. And last but not least, cams designed for a certain power range will help too. However, you will need to upgrade the whole head with springs, lifters, valves... and so on.

Also, if you're cruising at 50 and it downshifts to 3500, that's pretty good. If it downshifted once more down (to 2nd gear) you'd be redlining. Then, the car would sit there and try to shift to 3rd again, and you would lose more time between that. I don't think there's anything you can do to get it to downshift lower. I don't think you want to.