i have an '87 240Dl and i would like to remove the resignator and replace it with a straight pipe. A) how long is the resignator and B) i have a 2" exhaust what size piping do i buy?? have any of you done this?? i beleive it will help give me better performance and fuel economy

I just tried doing this today. I went to autozone and bought a 1ft 6in section of 2" ID pipe, which is the same length as the resonator. The ends of the pipe are oversized so they will slip onto the exsisting pipe. I'd tell you an easy way of freeing the resonator but I haven't found one yet... sparyed with penetrant and letting it sit overnight... so maybe tomorrow will bring success.
Adam.

Borrow or buy a Dremel tool (or pneumatic die grinder, if you have a shop air source)and use the mini-cutoff wheel. Most of the O.D. slip joints are partially slotted axially; just remove the clamp and lengthen the slot toward the part you're going to remove. Once you're past the back end of the inside piece (which belongs to the upstream pipe), spread the OD slip joint wider with a screwdriver, and tap the resonator aft... it should come right out. The main thing is to avoid distorting the pipe which will remain on the car.