I am thinking about purchasing the HKS Hi-Power Exhaust and Downpipe, however I do have some questions. The exhaust has 3" piping and the DP has 2 1/2" piping. I understand that the stock cat will bolt up without any problems. Will the RMR or Perrin test pipe bolt up to it? Does anyone have this setup, if so what hp increase should I expect with the stock cat? What type of numbers should I expect with a test pipe?

 

LOl........I have the exact same questions!!!...help us guys...

 

Try a search there is sooooooooooooo much on all this.

 

i remember reading an import tuner issue where adding a downpipe actually decreased horsepower but this was done without the aid of an air fuel controller so i recommend tuning your air fuel ratio when you install a downpipe