I'm a little confused, i've searched and found out that the S pipe removes the second cat.
http://www.planetmagnaflow.com/pdf/16640.pdf
is the instructions i'm using to install my Magnaflow catback exhaust.
Just a question though, instead of cutting 3.5" behind the cat, can I get a, let's say invidia or megan s pipe, and then just clamp the midpipe without cutting to the spipe?

Or am I completely wrong?
Oh, and this won't throw a CEL will it?

 

Alright, sorry, I found my mistake.
Heres a quote from another forum
So it's at the tip of the stock midpipe. Will I still have to cut before the cat? Even with an aftermarket s pipe? Seems stupid that I would have stock header, aftermarket or stock s pipe, piece of the stock midpipe with cat, magnaflow midpipe, muffler.

I'm just really confused, someone want to correct me?
thanks.

 

its before the resonator on mid-pipe. just take both off and put aftermarket in. you have stock header you are ok for emissions.

 

The magnaflow is the only cat-back that keeps the factory catalytic converter on the mid-pipe. You would have to get a custom piece made to remove the cat in the mid-pipe. Another option is to get a different mid-pipe (Megan Racing), but then you'd have to cut/weld the Magnaflow exhaust to mate up.

Something else I didn't like about the Magnaflow system is it uses different size piping (almost 2.5" in one section, back down to 2.25" in another). The Megan mid-pipe would resolve most of that though, but as I said above, would require cutting and welding.

If you look at most cars on the market, the catalytic converter is setup a little different than on the tC. Most other vehicles have a flange directly after the catalytic converter on the mid-pipe. The companies that sell cat-back exhausts sell the section that bolts up to the flange on the catalytic converter (hence the name cat-back (from the cat to tail pipe) exhaust). Since the flange after our catalytic converter is right before the muffler, we have axle-back exhausts, which some companies consider cat-back exhausts. Other companies that replace the full mid-pipe call their exhausts cat-backs, but are technically down-pipe back exhausts (the s-pipe is normally called down pipes on other vehicles).

 

it would be so much easier if the tc's had removable cats so we dont have to get custom midpipes done....but im sure we can do that ourself put a flange at the end of the cat

 

would getting a megan s pipe do much? like make it louder, any slight gains? and anyone know how much a new one is?