the reason I ask is because I am having a problem with my exhaust that was custom made and I don't want to deal with the same guy so I am going to look into purchasing one of the following: Greddy, HKS, or Stillen. IF you have one of these would you please let me know how loud it is with the y-pipe and if you have a mpeg that would be great. Also do they all fit the stillen ground effects on the rear of the car?