just some added proof to this...
I ordered an OEM pipe for my first m42, ran flawlessly for 80K miles.
Then I got rid of that b/c of body rot/rust, and went about doing the mess under the intake on my new m42. Bought the URO part from BMA b/c it was cheaper; thing SUCKED, it leaked like a bastard. So I went to the yard my old car was at and bought my old pipe back, put it in and no problems.