I currently have Fast Intentions HFCs on my G coupe. I am looking into made buying a used true dual CBE from Stillen. My only is concern is that the HFCs may make the exhaust RASPY. If I could hear peoples opinions about this I would appreciate it. Also what is the dif between Gen1 and Gen 2 and any other problems I may need to know about. Having no luck with replys in the exhuast section.