After-market E38 Catalytic Converter

[Big Blu]

I posted a bunch of technical details about this in another thread, but here's the short version:

OE post-header pips has an ID of 1.9"... it looks much bigger because it's a double-walled pipe. My new pipes are 2" and configured exactly the same length before the "V" as the OE.

This sizing is more than sufficient for this size motor; for comparison reference, the contemporary E36 M3 with 3.2l of displacent used similar sizing, and it had another 1200rpm. If you think about each half of the V12 as a 2.7l 6-cylinder, dual 2" leading to a single 2.5" is more than sufficient.

Of course, size alone is a simplistic way of looking at the situation that does not tell the whole story. In my experience, the very critical post-manifold tuning that BMW does is often spot-on. The primary inefficiencies come from the cat size/type and various crimps or restrictions that are manufacturing or sound compromises. With the shorter Magnaflow cats placed strategically, we get a longer secondary-V pipe length for effective retention of exhaust velocity before hitting the cats.

- Rob

Hello Rob. I visited your site 'UUC Motorwerks' seeking catalytic converters or a set up for my 1999 750iL. There is nothing listed on the site and I realize this thread is quite old, but any information you can provide for an upgraded exhaust is greatly appreciated.

[humanite]

hello rob. I visited your site 'uuc motorwerks' seeking catalytic converters or a set up for my 1999 750il. There is nothing listed on the site and i realize this thread is quite old, but any information you can provide for an upgraded exhaust is greatly appreciated.

bump!!!!

[Rob Levinson]

Hello Rob. I visited your site 'UUC Motorwerks' seeking catalytic converters or a set up for my 1999 750iL. There is nothing listed on the site and I realize this thread is quite old, but any information you can provide for an upgraded exhaust is greatly appreciated.

Sorry, we no longer offer the exhaust for the E38. I am not aware of any companies that still do either.

Worst case, you could have a custom exhaust shop construct one for you using standard performance cats and mufflers.

[Big Blu]

Sorry, we no longer offer the exhaust for the E38. I am not aware of any companies that still do either.

Worst case, you could have a custom exhaust shop construct one for you using standard performance cats and mufflers.

Thank you Rob and I'll check my area for custom exhaust shops.