Andy C
Member
Posts: 56
Registered:
2/19/08
Status:
Offline
From: KY
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11/1 5:47p
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I have a friend with a 2002 F150 with the 5.4 and he is wanting to cut his 4 stock converters off and put in 2 magnaflow high flow converters. Which magnaflow high flow converters does he need and what inlet / outlet size should they be. He wants to run 2 1/4 true duals.
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Thermo 
NOS Lightning Member
Posts: 11,250
Registered:
9/29/01
Status:
Online
From: VA
Truck: 1997 Expedition
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11/2 6:29p
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Andy, the factory headers are 2.5" piping. So, he is going to want some cats with 2.5" ins and outs.
Now, with that being said, as long as he sticks with the 2-1/4" true dual exhaust, he will be fine. But, I have a feeling that if he steps up to the 2.5" true duals and then decides to run a low restriction muffler, he may have issues. The truck will run fine. That is not the problem. His problem will be in the loss of low end power. This will kill any chance of decent mileage, especially in town. I would not be surprised if he sees his intown mileage drop into the single digits even with the 2-1/4" exhaust system if he is running say a 40 series muffler. If he is running say a 70 series, then he will be fine. The 5.4L motors are touchy when it comes to large/low restriction exhaust systems.
if you need more info, let me know.
Chris "Thermo" Coleman, Nukie the radioactive 97 Ford X, and K`RE Ann the 03 Jag X
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Andy C
Member
Posts: 56
Registered:
2/19/08
Status:
Offline
From: KY
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11/3 5:13p
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His plan is to run 2 magnaflow high flow cats with true dual 2 1/4 pipes no mufflers, just straight pipes. So he would need the 2.5 inlet and outlet even though he is running 2 1/4 after the cats?
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Thermo
NOS Lightning Member
Posts: 11,250
Registered:
9/29/01
Status:
Online
From: VA
Truck: 1997 Expedition
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11/4 3:18p
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yes, the piping up to the Y-pipe is 2.5" pipe. So, unless he is planning on redoing the piping all the way back to the cats, he will need the cats with the 2.5 inlet and outlet. If he is planning on redoing the piping to the cats, then he will need 2.5" inlet, 2.25" outlet.
Chris "Thermo" Coleman, Nukie the radioactive 97 Ford X ,and K`Re Ann the 03 Jag X
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Andy C
Member
Posts: 56
Registered:
2/19/08
Status:
Offline
From: KY
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11/4 5:47p
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He is cutting his old ones off himself and just wants to get the new ones welded in there place and have the true duals run after them.
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