Replacing Headers

The 351W headers from Factory Five leave a lot to be desired.

  • They’re mild steel, so even with the ceramic coating on the outside, they will rust from the inside out.
  • They’re only 1.75″ pipes which is fine for a 351W, but really not enough for the 427.
  • They are four separate pipes all the way down to the square flange where they mate to the side pipes. With an EFI system, you have to install the O2 sensor after the four pipes merge so that you’re sampling one whole bank of cylinders. That means the O2 sensor would have to be installed on the side pipes where it will show.
  • They’re not mandrel bent, so there are fairly deep tooling marks all over the pipes which makes them look like shit.

After a bit of research, we’re going to go with a set of custom headers from GP Headers; they’re better in every way.

  • They’re made from 304 Stainless for maximum corrosion protection and long life.
  • We ordered them with 1 7/8″ pipes to allow the 427 to breathe a bit easier.
  • As you can see in the picture below (from a Coyote engine, but similar design), they have a double collector which allows the O2 sensor to be mounted inside the engine compartment.
  • They’re beautiful! Ours will additionally be ceramic coated for heat and appearance reasons.

These are substantially more money than the FFR versions (nearly 3x the cost), but I think they’re absolutely worth it.

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