Mac VS STock Mustang Headers?

NOTYSC

Registered User
Anyone know how much of a difference there is between the stock headers off a 95+ mustang and the 99+ MAC headers for the mustang? Thanks, Dan

Anyone know the Primary and Collector specs on 90 SC headers, and 99 Mustang Stock headers? Thanks, Dan
 
Stock 94-98 3.8 Mustang header is a stainless steel unequal length shorty with ~ 1 1/2" primaries. At the head flange, the tubing is expanded way big to match the giant exhaust port size. Even so, the weld still slightly protrudes, so grind the excessive weld bead back. Each header has an O2 sensor bung in the collector. Driver's side EGR port. They will bolt right up to the SC heads, but expect to adjust factory y-pipe flange positioning.

The 99-up 3.8 Mustang is a tubular stainless steel manifold with similar O2 and EGR setup.

MAC's shorties are ~ 1 5/8" ID, unequal length headers with corresponding O2 and EGR stuff.
 
J57ltr said:
Here are the measurments that I have from these three different manifolds.

89' Tbird cast iron manifold. Mildly ported

ID of primary minimum dims 1.7165" X 1.1540" this is kind of an hour glass shape and the dim is up and down and across the smallest opening horizantally.

2.055" ID on the outlet.

96' & up Tbird manifold. Stock SST

1.3030"ID 1.4715"OD Has bends with a OD of 1.379" X 1.486" oval

1.7805"ID on the outlet could probably go to 2.00"

99' & up Mustang tubular manifold . Stock SST

1.235" ID on the inlet. In order to make this figure larger you would need to weld a bead around the outside while still leaving room for the bolt to attach it to the head.

1.4455" OD primary tubes gets larger as it starts from first cyl to last cyl.

1.7410" ID outlet maybe able to open to 1.8" and it would take rewelding the outside of the flange to the tube to open it any more.
 
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