bennny

How big is this pipe? I need to know what size piping to go with for my cat and muff...thanks

Terran

iTrader: (6)

2.5 if I'm not mistaken. It should say on their website.

Brudaddy

iTrader: (2)

It should be 2.5".
You don't want to get too much larger diameter than that on a NA car or you will defeat the purpose. If you are turbo or Supercharged, you could go with 3" and still benefit from it.

I would recommend just leaving the stock cat on there with the stock resonator. Go to a local muffler shop and get them to custom bend you some 2.5" piping back to the muffler. Keep the stock muffler on there. (by keeping the stock parts that I said, you will probably only not realize about 1hp difference. Not worth the trouble or money for that much). They should be able to do the piping and make it all fit back together for like $50 or so.