Just as an FYI to owners of 1997 to 2004 Heritage F-150s. If you examine the Exhaust just after the Collectors you should notice that the pipe diameter drops down to 2.25 inches in the bend just before the first cat. Any exhaust mod should take this into consideration.

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so it SHOULD be 2.25" all the way?

 

The collectors are 2 1/2 inches then in the bend it shrinks to 2 1/4 then it goes back to 2 1/2 inches for the rest of the exhaust.

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Ford FAIL.

 

Would that be because the pipe is not mandrel bent?

 

Nope.

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All OEM Ford exhausts are this way. My '04s was. Just a crap job. But everything after the Y pipe is OEM mandrel.. Makes sense? No I didn't think so either but they did it that way

I haven't been able to measure and inspect an '09+ yet so I am unsure of those, but they are confirmed 2.75" out the Y pipe with much shorter converters than '05 - '08.

 

great...well looks like when it comes time to replace my Y pipe I'll get one custom made to 2.5" all the way. My mech has access to a mandrel bender so he can fab up the pipe no prob. Good info jmc..I never even thought to check it out.

 

With a little 4.2L I would keep it 2.25" throughout. But for a single midpipe leave the stock 2.5" as is.

The 2.25" restriction is in the left bank in the Y pipe also. So eliminate it you need to replace the pipes from the cats to tailpipes.

 

Thanks darren. My cat back has a 3" inlet to the muffler and 2 2.5" outlets, the pipes after the muffler are also 2.5" up to the 18"x3" tips. I prolly lost a bit of back pressure but I can live with it.