I agree with Todd. I did the cat-back replacement as well as the exhaust system change to MagnaFLow and removed the resonator. The system has a nice quiet rumble until you step on it and it has a nice kick to it along with a growl I like. If you are not stomping but in 4th gear (not overdrive) there is a nice rumble. All on all I love the increased performance, sound and look. It's well worth the cost.
They don't make a kit for the adren, So I went with the cut in.... I removed the resonator and muffler and installed the 17" I believe Magnaflow stainless muffler.
It was MagnaFlow from http://performancepeddlerwholesale.com here is what I paid and what parts ordered?..
MAG93404 93404 1 $270.47 $270.47
MAG16773 16773 1 $437.90 $437.90
I had to take the muffler and pipes to Midas as the local shop does not handle welding. Midas does a great job doing this work. It was not cheap but it was flawless and looks great. The muffler includes the two tip exhaust pipes and they look great. The cat-back is a direct fit for the Sport Trac while the muffler and pipes are for the Explorer. The hanging hooks are in the wrong place for the Sport Trac so that is why the welding/cut in option at Midas. So, beware this will require welding new hangers so it will fit the Sport Trac.
Oh. Gotcha! I thought this was for the V6. I was wondering what exhaust upgrade can I make to the exhaust on my 4.0 without making it sound like a rice rocket??