i have not done the center one but i think some others have. and i think the answer is yes to a straight pipe.

i have done the rear on two of my benzes with straight pipes and been satisfied with the results. my 90 350sdl and my 84 500sec. both a little noisier but not harley loud.

tom w

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[SIGPIC] Diesel loving autocrossing grandpa Architect. 08 Dodge 3/4 ton with Cummins & six speed; I have had about 35 benzes. I have a 39 Studebaker Coupe Express pickup in which I have had installed a 617 turbo and a five speed manual.[SIGPIC]

..I also have a 427 Cobra replica with an aluminum chassis.