James Bailey

exhaust manifolds 1980 928/ 2008 Mustang 315 hp 4.6....not much change in 30 YEARS . Internal diameters are much the same the D port being the major improvement.

Imo000

The collector flange is better. No gasket.

IcemanG17

but look at the sissy bore spacing on the Ford....

danglerb

Not much "apparent" change, can't really argue that 315 hp isn't some serious change.

James Bailey

Yes small block Ford ! next year they get the full 5 liters in the modular motor that should get close to 350 HP for the GT.

MM951

Nice car FS!

I read 413hp out of a 32V DOHC 5L for the new Mustang GT. Nice jump from what they have now...

KenRudd

Just curious, what improvement does a D Port bring to the table?

James Bailey

Some think a well designed D flows 10-15 % better than a round port. Some put a round tube exhaust manifold on a D port in the belief that the step in the head (flat of the D) reduces revision of the exhaust pulses back into the cylinder (esp with high overlap big cams) so you get a better intake charge.