ivangene

WTF is with that stock 997 thing.... that looks like a plumber designed it, not a high performance exhaust flow engineer ??

is there some "new math" in determining the length of pipe needed... the middle seems a "bit short" of the 2 ends????

SH || NC

Agreed. I'd say the 996 are really damn close if not the same to the 997 X51

jhbrennan

I think the stock headers on 3.6l 996 have an outside diameter of 42mm while the X51 headers on the 3.6l 996 have an OD of 48mm - I know they have a different part number - don't know about the 997.

chsu74

I was told that the reason X51 headers are inexpensive because they are cheaper to produce. Typically, you would want the pipes to be the same length out of the engine into the cat for optiminal performance. That is why Fabspeeds are $1600 new compared to the X51s.