Okay, so today I bought a used cobb cat back. The midpipe on this catback only has one flange on it, and one end was I guess welded onto the downpipe. Tomorrow I plan to get a new flange welded onto the midpipe, but my question is, are the two flanges the same size? Sorry for the newb question but i havent had the car for too long =P.
-John

 

A competent muffler/exhaust shop will have any flat flange you need for the exhaust components to mate up. The front flange might have to retain the 'donut' gasket to mate to the stock downpipe. It's been a while and I can't recall exactly where that donut gasket flange is located but you'll know it when you see the fasteners with small springs on them for pre-load.

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