Fast xfi
Can you do it without one? Yeah, but its kinda like going back to a carb. Theres no fail-safe to help reduce the chances of the car stalling at a bad time.
Is it pretty stright forward as to the setup as in fill in the parameters and let it sort things out for its self or is it going to be more involved
does the power adder function add fuel to the base table or does it switch from the base table to the power adder table. IE does one need to include the required NA fuel+nitrous fuel or just the added fuel required for the nitrous.

