I have a 1998 Expy EB, 5.4L, 4x4. Yesterday, I had a muffler shop install a Magnaflow muffler and 3" pipe exiting behind the passenger-side rear wheel. I'm very pleased with the sound. I had a Flowmaster on my Bronco, 302L, and this baby sounds much better. This shop sells Magnaflow and Flowmaster, but he said the Magnaflow's are, by far, their best sellers.

At idle there is essentially no increase in sound over the factory exhaust. However, when you start opening up the throttle, those ponies start speaking with authority. At WOT, it's NICE. As far as resonance is concerned, at 70-75 mph (around 2100 rpm) there is a little resonance, mostly audible if you lean into the rear seat area. From the driver's seat it isn't objectionable at all. I have a standard rule that, if the ignition switch is "ON", the subwoofer on that Mach audio system is thumping anyway, so I'll never even notice what little resonance there is.

I installed a K&N filter on it last week. On Monday coming up, I've got to drive the Expy from Burlington, NC to Birmingham, Alabama. This will be a good gas mileage test.

As far as increase in gas mileage around town, I don't think the combination of K&N and Magnaflow is going to help...in fact, the mileage might actually go down. Every time I take off from a stoplight, I'm wanting to open her up and "let them ponies speak". Does anyone else have this problem? :P

Ken

1998 Expedition EB, 5.4L, 4x4
Affectionately Known As "Land Yacht"

Magnaflow
K&N

 

I've got the same problem now. Ever since I put on my Gibson exhaust I can't keep my foot out of the throttle. I'd also like to give you a early welcome to Birmingham. Maybe we'll see each other stuck in traffic on I-65.