Controlling the upper injectors isn't necessary. It is a worth a little bit of power, but we're not talking huge differences. Especially for the additional price. I was asked about the secondary module on another forum, and personally I think I'd buy the ignition module, followed by the quick shift, before the secondary fuel module, it's definitely at the end of the list. That being said, I'm not sure I'm going to be willing to drop that kind of money for more add-ons at this point. For all that money, I'd be tempted to add a YEC, and still just fine tune with my PCV and AutoTune on top of that.