I would suggest running (not walking) away from Magnaflow on an Expedition. I had their 3" mandrel bent cat-back on my 2005 and couldn't stand the drone. Mine you, I like loud, and have flowmasters, spintechs, and Corsa on my original Shelby GT350, BOSS302, Paxton Viper, etc. and straight pipes on one Harley, but the Magnaflow didn't work well in a daily driver Expedition IMO. I beleive the main issue is the large box-like interior volumn which amplifies the drone. I've driven F-150s with a similar setup and they weren't bad, probably because the muffler was beyond the smaller cab and interior, but I just couldn't stand it in the Exp. The drone was from like 1700 to 2100 rpm, or 55-75 mph. Ended up cutting out the 2 month old Magnaflow high dollar muffler, throwing the POS in the trash, and replacing it with a Stainless works muffler. Still a little drone, but tollerable for a DD. Good luck..
Before this I had a Impala SS (5.3L V8) with cylinder deactiviation and a catback magnaflow.. . . .talk about drone . . .. at highway speeds it shut down 4 cylinders and sounded like helicopter rotors.
I was looking at a Magnaflow myself. I've also been scouring the net, tube, etc trying to find vids or audio clips that were half-way decent. There ain't much! There is a decent Flowmaster clip on an Expy that doesn't sound too bad but I've never been a huge Flowmaster fan. When I sold my 90 notch many years ago, it had Dynomax Ultra-Flows on it that just sounded the absolute nutz with hardly any drone inside at all. I've thought about going to one on the Expy but I know the lack of the H-Pipe and true duals will change the personality of that sound quite a bit.
Decisions, decisions, decisions. I may stop by Lou's Custom Exhaust up here in Manchester, NH to see what they have. They're one of the biggest aftermarket exhaust builders around here and come pretty highly recommended so it might be worth a shot to stop by and see what they have to say.
I have a Dynomax cat back exhaust for my 5.4 Expedition and I love it. It has a stainless flow through muffler which is very quiet when under light throttle but it gets a lot louder when you open it up. It is a very deep sound, not tinny like some mufflers. I got if from Jegs a while back for $200, and they had a $75 dollar rebate when you bought an exhaust from them, so I got my exhaust for about $125 dollars! It has a polished stainless tip welded on the tailpipe, and the rest of the piping is aluminized steel. I really love the way it sounds and there is little to no drone in the interior.
Hi guys,my Supercharged 07 Limited has Gibson headers,hi-flo cats and a flowmaster 3" that splits into 2 pipes 12" before exiting the rear side by side.(see pic's in my garage) I needed to let it breathe but did not want noise and drone.I'm happy to say I got both wishes.Truck haul's *** and sounds great but doesn't overwhelm.I'll be home in a few days,I'll post pic's and a video,Eddie I'll get you a model number for the muffler,works great.