For an '09 stock MCS owner with an opportunity to buy a full turboback or catback exhaust removed from an '09 factory JCW car, is there any advantage to using the factory JCW downpipe? There are different part numbers on realoem.com, 18307583146 for the JCW, and 18307558755 for the MCS, but I suspect the only difference is the gasket and mounting flange on the face that bolts to the turbo. If this is the case, it would appear to be an easier install for the catback portion only, no messing with the O2 sensors on the downpipe and post cat. And likely less knuckle scraping with catback only.
Anyone care to hazard an opinion here?

 

Hector at Exhaust Depot should know, he is the man

 

The DP on the JCW and MCS look 100% identical, i wound not be amazed if indeed they had a different part number. The JCW has no second cat in the catback system, however the MCW does.

So could it be that the JCW has more precious metals inside the cat or that the jcw ecu is tuned to dish out less emissions.

Regardless both systems are interchangeable so you should be a happy camper.