I have not used the FAST system, so I really cannot add much contrast, however, I will try and help the OP with the decision making. First of all, if the OP asked this same question on the LV Buicks page, then I will repeat what I stated on that page: It depends on your goals, how much you want to spend, and if you want to learn how to tune yourself. I understand that most aftermarket systems require the end user to learn how to tune, or with the proliferation of the FAST systems, find someone to tune it for you. The SFI6 seems to be gaining some popularity, and the code used with this system is derived from the same base code as the EBL, AFAIK, so other EBL users can help tune out a bug or diagnose any other anomalies encountered. There is a following at the TGO, which is where Streetlethal also helps other EBL users tune their cars, so the OP can explore other EBL topics over there as well. The SFI 6 uses a factory ECM found in late 80's Buick powered cars, but modified with EBL board, and can be installed either by the end user or Dynamic EFI staff. There are also is ADC 0-5v channels that can be added to the datastream, i.e.; WBO2, EGT(s), fuel pressure transducer, or pretty much anything else that uses 0-5v, AFAIK. The SFI 6 can also drive an alky system, like SL stated, which is what I use as well. Alkycontrol has a very nice kit, but I prefer the DIY approach, so I bought a basic alky kit without a controller and used the SFI6 to control the pump, so far it works really well, although I only spent one day tuning it so far. Also it can use the factory boost solenoid if needed. Also, SMOG stuff like CCP, and EGR can be used if needed, just in case. VE learn can be used to dial in the off boost VE table, with either BLM or WBO2. Higher resolution tables as opposed to a basic bin definition, but I don't see very many DIY chip burners on this board. The price is right for me, and I know I can get a question answered fairly quickly by another EBL user, and the Dynamic EFI staff, so support is fairly robust, IMHO. Feel free to explore the dynamic EFI page for information, and ask any questions for clarification, you can also browse the SFI6 topics in this forum, one of which is my own. HTH!