Originally Posted by FP
You will get a lot of input on this as folks chime in. I have the sprint booster, and it's great. However, the SB does not increase your horse power. It only eliminates or greatly reduced the lag when accelerating, while the ECU mod increases horse power by about 20. So in that respect I would say they compliment each other. This is a base explanation from 25,000 feet. I'm sure you will get more advice from others that are more technical.
You nailed it right on the head...