Why? The factory exhaust flows really well, it may even be 3" already. Look up some youtube videos from dieselpumpuk where they are getting huge power out of these engines. There is one where they talk about the stock exhaust and how well it works. IIRC stock exhaust is good for ~450 hp, which you'll never even come close to with the stock turbo and stock injection pump. Exhaust is the very last thing that needs upgrading on these cars.

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1998 E300 turbodiesel

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