Dfi has the advantage of letting YOU program the a/f ratio you want basically and can correct up to a certain point if your fuel program is off. However which ever system you go with the oxygen sensors are not leaded fuel friendly and will cost you alot to replace them. Be prepared to spend hours on idle and cold startup settings just to get the car running. The new fast system is very nice along with the gen 7 dfi, but your going to spend about $1600-$2500 depending on the options you want. People have gone low 9s using the stock computer it all depends on how much patience you have programming it the hard way with your chip maker, etc. I have a gen 6 dfi system, a gen 7 dfi system and a fast system presently and each has its plus and minus's.
