I'm trying to understand the 'silencer' on the mid pipe and whether it is infact a silencer (reduce noise) or is it a true second CAT (which seems unnecessary on a 4 cylinder normally aspirated stock motor).

Does anyone have a schematic of the TC2 exhaust system? The CAT as far as I can tell is part of the exhaust manifold and is monitored by the engines ECU. The 'silencer' appears to be exactly that...a silencer to reduce sound versus an active catalytic converter and is not connected to the ECU or emissions systems.

Anyone have definitive information one way or the other? So far I've only seen anecdotal feedback here on the board....

 

From what i saw i there are 2 things in the midpipe. the first is the secondary cat and rite after a resonator.

 

It wouldnt have a MSRP of $874 if it was just piping with a resonator. http://www.trademotion.com/parts/201...w=21&maxRow=10

 

In looking at the schematic, the mid-pipe has the CAT followed by the silencer...answers my question, there is no second CAT.

 

On the TC1 it's Top Cat that that gets checked by the secondary O2 sensor. Then you have another Cat at the bottom of the midpipe. Then a few feet down you have a resonator or silencer, then you have the axle back exhaust.
I gutted the second cat on my TC1. Two cats and a resonator...give me a break.

 

^This. Catalytic converter number 1 is in the exhaust manifold, catalytic converter number 2 is in the midpipe, then the resonator right after it. If it was only a resonator in the mid pipe it wouldn't MSRP $847, it would be maybe under $300.

 

Agreed. So that being said, can I remove the resonator (after the second CAT on the mid pipe) and still be legal....in CA. The only thing we can't do in CA is remove/replace the OEM CAT(s) so I expect that's fair game.

Anyone have any feedback on removing the resonator on a TC2?

 

Opinion/speculation, perhaps there are two cats... I remember reading about the dezod catted header.. How they elaborated on the cell count being less than stock. So it occurs to me that perhaps the designers thought to have two cats with less cells than one with many. Think of how long your intestines are.. They are that long cause the only absorbing power comes from the limited surface area of the liner. So if you reduce the density of the filter and compensate with a longer filter, in order prevent a bottleneck and keep a consistent flow would seem logical to me. I vote that there are more than one in our sport tuned exhaust.