Tim: Others with more experience will probably chime in, but I would NOT want a "factory exhaust system" for my 71 280SL. For one thing, it may no longer be available, but even if so, the factory exhaust was welded together, and I would not want this again on my car. A "slip-together" with an easier installation and option to replace parts of it would be my prefrence. Then, the stainless steel version, which is being offered by one supplier would be my choice.