I have an 03GT obviously, with 2 chamber flowmaster mufflers and stock headers on it, I am going to purchase the Mac Pro-Chamber, and haven't decided whether I want the off-road or with high flow cats, my question is, if I get the off road pro chamber I know that I need to get the MIL eliminators, but do I also need to get O2 extensions as well? And if I get the high flow cats, I shouldn't need the MIL eliminators but do I need the O2 extensions, any help would be great, thanks.

 

yes you will have to get 2 o2extensions because the o2 sensors are right by the prochamber as where the stock h pipe is closer