987 Exaust Manifold on 986 3.4L

[insite]

Originally Posted by Johnny Danger

What is the diameter of the primaries ?

42mm if i remember correctly

[BYprodriver]

Originally Posted by insite

42mm if i remember correctly

That's the size of my NHP manifold with sport cats at the inlet.

[Johnny Danger]

Originally Posted by insite

42mm if i remember correctly

That's small. I run 2.25 inches from the flange, through the primaries - all the way to the catback. The catback has 3 inch inlets and 3.5 outlets.

[BYprodriver]

Originally Posted by Johnny Danger

That's small. I run 2.25 inches from the flange, through the primaries - all the way to the catback. The catback has 3 inch inlets and 3.5 outlets.

Not the Hemi 'Cuda, the Boxster.

[Johnny Danger]

Originally Posted by BYprodriver

Not the Hemi 'Cuda, the Boxster.

That's my exhaust configuration - built and designed by M&M Exhaust in Germany who are the preeminent tuners for the Porsche Super Cup, Carrera Cup Deutschland, ADAC GT Masters, ALMS / LMS, VLN / BF Goodrich, FIA GT and Rallye Meistershaft race series. They also produce the current Cup S, Cup R and RSR exhausts for Weissach.

[BYprodriver]

Originally Posted by Johnny Danger

That's my exhaust configuration - built and designed by M&M Exhaust in Germany who are the preeminent tuners for the Porsche Super Cup, Carrera Cup Deutschland, ADAC GT Masters, ALMS / LMS, VLN / BF Goodrich, FIA GT and Rallye Meistershaft race series. They also produce the current Cup S, Cup R and RSR exhausts for Weissach.

That's WAY to big for street driving. That's killing your low rpm torque.

[Johnny Danger]

Originally Posted by BYprodriver

That's WAY to big for street driving. That's killing your low rpm torque.

To the contrary, my low end and mid range torque increased significantly. Keep in mind, that I still have cats in place (HJS 200 cell) in order to maintain sufficient back pressure.

[stephen wilson]

Interesting, that's contrary to everything I've ever read about exhaust tuning. I'm sure you know there's much more to pressure wave scavenging than just backpressure. Those are big-block V8 numbers.