Yeah, it doesn't make sense. Everybody reports power gains with the 328/M3 mid-pipes and cat backs over the 323 units. Haken is literally the only person I've ever heard say that the 323 exhaust is better. His claim doesn't add up, nor should it. BMW would never put a more restrictive exhaust on their higher performing models.
Also, how is cross section different than area? I'm assuming that the terms are not synonyms, but when I calculated the are using Pi*radius squared, it produced the same numbers as your cross section figures. Sorry for being dense...
EDIT: That makes much more sense! Haken said the 328 pipes were 1.5" each, but those photos are showing that they're much bigger than that. I think he was suggesting that they're double-walled, and that the inner pipe is only 1.5" in diameter, but that's not what we're seeing in the photos.
1998 BMW 328is
1966 Pontiac GTO
2007 Subaru Impreza 2.5i 5-door
View my photos: Caught in the Wild
Last edited by ZeGerman; 02-15-2013 at 04:42 PM.