Well I put First Gen W126 500SE true dual manifolds and downpipes on my 560SEL. Welded the pipes into the OE catalyst.

My 300SD has the dual 'kidney bean' resonators your describe, but single pipes in and out.

Soooo... I say yes, what you are thinking will work. I would go the extra step and uncork the motor under the hood too. The crossover pipe on the 560 was only 1-5/8" once I removed the heat shield. TINY. Hampers power and economy. Comical really. Not sure why MB did not run actual dual manifolds with dual precats, then into a single cat.

Now of course, the true dual log manifolds will not make as broad of power as the four piece units off the 300hp 560, but hell...it certainly uncorked the motor big time. I have sub $150 into mine including new copper nuts.

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I'm not a doctor, but I'll have a look.

'85 300SD 245k
'87 300SDL 251k
'90 300SEL 326k

Six others from BMW, GM, and Ford.

Liberty will not descend to a people; a people must raise themselves to liberty.[/IMG]