Some of you probably heard of this from my posts on the other expedition forum so I'm sorry for repeating myself. But for everyone on this forum I wanted to share my experience/idea.
Basically I removed the restrictive factory "Y-pipe" and the rear two converters (mine had 4 cat converters stock). I now have two separate 2.5" pipes flowing, 1 from each side of the engine, back to a dual inlet SPINTECH muffler. It has one large 3" outlet. The 2003 expedition can't fit dual exhaust unless you remove the spare tire, or run side pipes forward of the rear tires.
From several muffler test reports/reviews I've read through it seems that Spintech flows about more than double what the stock muffler can flow. Also, each rear cat converter is only capable of flowing about 1/3 that of a straight pipe. On top of that, I stole the factory design of my 98 explorer which was ordered with the supposed "performance model SOHC v-6", it had a dual inlet high flow muffler instead of a Y-pipe.
I've had Flowmasters before (3 chambered) and I really loved the sound. But after hearing this Spintech I'll NEVER use another Flowmaster, especially after how poorly they performed in the CFM comparisons I read.
The bottom line is that I feel like I gained some power, I gained approx 2 mpg, and the sound is unbelievably cool. It's quiet at idle, very deep at part throttle, and crisp/racey at high rpm. On the highway you can definitely hear it, but it's not the slightest bit annoying.
The mufflers are designed differently than any other muffler, so they're not restrictive like typical mufflers and not straight through like a glass packed. They flow slightly less than magnaflow or dynomax, but double the flow of flowmaster. I opted for the Truck/RV 8000 series because I wanted it to be quiet.
Just wanted to let you know I had success with it, any questions let me know.
Basically I removed the restrictive factory "Y-pipe" and the rear two converters (mine had 4 cat converters stock). I now have two separate 2.5" pipes flowing, 1 from each side of the engine, back to a dual inlet SPINTECH muffler. It has one large 3" outlet. The 2003 expedition can't fit dual exhaust unless you remove the spare tire, or run side pipes forward of the rear tires.
From several muffler test reports/reviews I've read through it seems that Spintech flows about more than double what the stock muffler can flow. Also, each rear cat converter is only capable of flowing about 1/3 that of a straight pipe. On top of that, I stole the factory design of my 98 explorer which was ordered with the supposed "performance model SOHC v-6", it had a dual inlet high flow muffler instead of a Y-pipe.
I've had Flowmasters before (3 chambered) and I really loved the sound. But after hearing this Spintech I'll NEVER use another Flowmaster, especially after how poorly they performed in the CFM comparisons I read.
The bottom line is that I feel like I gained some power, I gained approx 2 mpg, and the sound is unbelievably cool. It's quiet at idle, very deep at part throttle, and crisp/racey at high rpm. On the highway you can definitely hear it, but it's not the slightest bit annoying.
The mufflers are designed differently than any other muffler, so they're not restrictive like typical mufflers and not straight through like a glass packed. They flow slightly less than magnaflow or dynomax, but double the flow of flowmaster. I opted for the Truck/RV 8000 series because I wanted it to be quiet.
Just wanted to let you know I had success with it, any questions let me know.
