I am going with a VAFC for now, but I'm seriously looking at some ITBs for a future upgrade. If I go for those, I'll need a standalone ECU. I don't think that even the eManage can handle ITBs. Even if I upgrade to ITBs, I'd still like for the car to be street legal. And in order to do that, it has to pass inspection... which, from what I understand, requires that the OBD-II port reports a "ready" code and does not report any errors. So far, this "piggyback" solution has been the only alternative that I have seen which shows promise.

chris_barry- Thanks for all of the feedback you provided. That provides some interesting insight.