I know I should have measured the diameter of my exhaust pipe before I ordered but I didn't. I have an '03 5.4 FX4. Before ordering, I carefully researched the magnaflow exhaust systems for my truck and all the systems I found show SI 3" DO 2 1/2".

I measured the pipe on my truck last night - 2 1/2" at the front of the muffler. Do I need to exchange this muffler for a 2 1/2" or do I have the right size?

Ford One

 

The cat-back kits get 3" intermediate pipes. You should convert yours because its much healthier to run. Get the Magnaflow Y connctor thats 2.5" dual in, 3" single out, and run a straight 3" pipe to the muffler.

 

Darren

I'm confused, I looked at the Magnaflow Y connectors but I don't see how they will help in my situation. I have a single 2 1/2" pipe where I'm taking the old muffler off. I want to join my 3" SI 2.5"DO. I've seen how muffler shops will try to cram two pieces of pipe together. I want to make sure I have male to female fitment from the old pipe back. I'm having trouble finding a part that will accomodate this. Any other suggestions appreciated

Ford One

 

I believe this is what Darren is talking about. http://www.performancepeddler.com/de...CT_ID=MAG10778

When Darren was saying is when you get a cat back system from magnaflow instead of just a muffler, you get the muffler you got, plus the MAG10778 Y-pipe connector, plus mandrel bent piping. What you need to make yours work with the muffler you have is this Y-pipe connector. It will go dual 2.5" in from the manifolds then 1 single 3" out to the 1 single 3" in on your muffler then 2.5" out back on both sides to the tips.

 

Precisely. If you have a 3" inlet muffler, you should have the mid pipe entirely 3". A 3" exhaust is healthier for these trucks, retains great velocity, and a nice note. The stock Y pipe kills performance due to its cheap single size design, does dual 2.5" merging to single 2.5" sound like it flows good? No it does not. The Magnaflow Y connecter would be better, and you could get the 3" mid pipe done at the same time.

 

OK, I see what you're talking about. I didn't see the existing Ypipe when I measured. Is
the 3" mid pipe something I need to order from Magnaflo at the same time or is that something that most muffler shops would carry?

Thanks again guys,

Ford One

 

Muffler shop will take care of you for a decent price. Should be around $100.

 

Unbelievable!! I ordered MAG 10788 from Sumit racing yesterday afternoon right after lunch. I hesitated, but only for a second, at the "Over night Express". Long story short - I got an Email that it was shipped at 4am and I had it on my doorstep at 1pm today. Cudos to Summit and Fed Ex.

 

Summit does have quality serivce. I'd proud to wear their apparel.