ok it's the hissing noise and I found out this is normal. It's not that bad actually! I also checked and it's not coming from the HFCs it's coming from the exhaust where the mesh is.
My cousin who drove with me actually likes it cause he says it sounds like a blow off valve lol

 

Q8y_drifter Guess what bro. I turned on my car today morning and my Engine light came on I guess it took a day for it to figure out that I have HFCs!

Sucks! I just don't get it how come yours didn't go off like mine did! Kinda pissed at it, but still love my Invidia cats.
I guess Im gonna go ahead and buy the extenders for the O2 sensors, hopefully that will fix the problem.

 

The CEL is kinda the norm it seems with these cars, I'm surprised I didn't get it though. I don't know if I should be worried about not getting it or what LOL

 

man this cel is killing me lol! I've even installed the non-foulers and it still popped up next day! pissed me off!!! I didn't put the steel wool but still WTH!!!???

 

I've bought the Invidia High Flow cats Non-Foulers, and did the installation today! complete PITA!!!!!

 

Did the installation today? Thought you did that a year ago from your post...lol...WTF