Shakenbake

Had the muffler off and noticed what looked like a spot of stainless steel showing through the normal road crud. Started a wire brush and it looks like this might be a stainless steel muffler. I found the following stamped on the muffler "Bischoff 911.025.01/274" also, to the left of that stamp was "911/1" Is this the stock muffler for a 1974 911 coupe or was this an upgrade by one of the previous owners? Any help in identifying this would be appreciated..

Chris Baker
1974 911 Coupe

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Shakenbake (Chris Baker)
1974 911 Coupe