To make any sense the cut out needs to be before the muffler. You would need two one for each bank (or add a combining y pipe and another to split back to the two mufflers. ).

I don’t know enough about exhaust systems to advise on if combining Into one pipe and splitting back would be a problem for the system to work properly and I would not recommend mixing the two banks together without somebody with history and experience doing exactly that procedure.

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2011 E70 • N55 (me)
2012 E70 • N63 (wife)