I am using a Apexi pen type TT and let me tell you. It reads the voltage off of the rear 1v(Narrow band) O2 sensor, and calculates a a/f ratio from that. It is SPOT ON with the dyno chart!
A delta dash would be a great tunning tool. I am considering getting one myself.
My car pulls so much damn timing that I can't even get off of the line without bogging...even from a redline launch! I noticed that if I reset the ECU, it runs alot stronger off of the start, but mellows out over time. Directly the opposite of what it did with stock injectors. On the stockers, if I reset the ECU, it was a dog, and then picked up over time.
I feel that the SAFC is a viable tunning tool, but you have to understand that that it is not static. It has to be constantly tuned because the stock ECU is so dynamic. That is where the DD is going to help you. Tune for the times baby...good luck!
Where are you going to get the DD from? I can't seem to find a retailer.