if you are going to to use a si ecu, then tou will not need the v-afc unless you really want it to lower vtec point etc... as the si ecu will cointrol the vtec point you and does have a nice fuel curve too, and if you want to use the v-afc a chipped ecu will give you a little better results. or have a chip done for what you want to do with the engine. the ecu you would use would be the p28.