I was going to order the Stillen exhaust for z arriving in couple of weeks but after reading about the F.I. I am confused and undecided. i will be adding CAI and not intrest in adding HFC. can you guys chime in give me some help on the choice. also what is the purpose of resinators on F.I. and is that required or does that help on performance. does Stillen system have resonators? confused