I looked at the exhaust system of our car while it was on the alignment rack. It appears as though there is no flange after the catalytic converter. It's all one piece from the downipe connection through the flexpipe, through the cat, resonator and muffler...no joints!

That said, it also appears very easy to replicate (no major bends) and just get something sleeved on after the cat...

 

From the official photos taken at the U.S. Press Launch

 

Yep. Of course, I'm an autocross-weenie, so I'm trying to work with Solo rules which state you can replace anything downstream of the cat. And that "bomb" right in front of the resonator at the bottom of the pic is the secondary cat.

 

Hey Per,
Glad to see you got your car.
So you got confirmation that the "bomb" as you called it is a Cat?
Have you talked with Lee yet?
Thanks for keeping us other autocross weenies up to speed!
Mike Potocki

 

I haven't looked inside yet, but that's my understanding.

Lee and I are working out a time when I can drive our car up there for prototyping.

 

http://www.realoem.com/bmw/partgrp.d...31&hg=18&fg=10

They do call it a cat. It looks like they have a replacement without one. JCW?

 

Does the secondary cat appear to have an O2 housed inside of it? The reason I ask is because I wouldn't mind removing that one unless we think its going to make the CEL go off, I for one don't want anything to do with that. That stock exhaust system looks very restrictive and I'm sure you guys are going to get it figured out for all of us.

I thought it was going to be possible to change out everything after the flex pipe, but now I'm not too sure. I hope I don't have to settle for changing out just the muffler because not only do I want to give the car an aggressive sound, but I wouldn't mind picking up some hp/torque, mainly torque.

 

Next week we are taking our R56 to the dyno to try three different setups: resonator only, muffler only, and straight pipe from the second cat. I'll post the results.

 

If true, it would mean the muffler can't be replaced without either replacing to cat or cutting and joining the pipe - doesn't sound right

 

All of the current BMW products come from the factory with one continuous piece of exhaust behind the first cat. To replace a single component, you must cut & clamp.

 

Any idea whether the Milltek cat-back is from the first or second cat:
http://www.millteksport.com/exhaust....?variantid=221
It lists front pipe & center section as separate components which sounds a lot if it is from the 2nd cat. This is significant for G-Stock rules.

 

The Milltek joins the system after the primary cat. The secondary cat is eliminated. I installed the turbo-back on our car a week ago. -Pete, Stratmosphere. 1.866.533.1777