987 Exaust Manifold on 986 3.4L

[Johnny Danger]

Originally Posted by insite

i am pretty sure the headers i'm using are sized right for my 3.4L. i am, however, obviously down on power compared w/ 996C2's and Cayman S's (they pull my on the back straight at road atlanta). since my headers are cheap ebay headers, they were my first suspect. i ran some calculations, though, and i'll be damned if they aren't a GREAT design for the 3.4L.

i just ordered a wideband o2 sensor so i can check to be sure the 996 tune is working right w/ my setup. with my intake & exhaust, this thing should be breathing very, very well.

What is the diameter of the primaries ?