Apexi Safc are an ok product and are an Interceptor, but you are limited in options and tunability. They intercept the inputs going into the factory ECU in order to give the right amounts of fuel and air ,etc to give you most power wherever you want it. However, it is ok for minor mods like you have done but if you want to do any more then this the factory ecu will start getting a little annoyed becuase the SAFC can only change limited things and as soon as the factory ECU starts picking up on other values changing and tries to correct everything towards what the inputs the SAFC is doing ,thus itl make you loose power or limit the power (in a wierd sense). Of course if this is the way you would like to go then by all means go for it . at this moment in time in your buld you will see gains with a good tune.Howver i would recommend going the whole 9 yards and getting a proper ecu of some sort but this is obviously dependant upon you and your budget of course.
What about an Adaptronic ECU? =p cheaper then a power Fc by far and very effective with numerous function up and beyond the SAFC since its a full ECU with adaptive capabilities as well. Its a good ECU in the long run. Im not trying to be dodgy or sell you anything but just mentioning it to you incase you would like to look around and see what is on the market that may fit your budget and a little more effective.
A Tune is vital and that is costly as well, so you need to add up those costs as well when you think about buying a ECu,piggyback,Chip or interceptor
hope that helps.
