Welcome, Eric, and congrats on fining two solid Explorers to work with.
As 410Fortune said, the factory manifolds are terrible. The whole stock is exhaust is bad, 2.25" dual into a single 2.25" muffler/tailpipe is too small for a V8. It's all fine for stock factory goals, but that doesn't apply to 99% of owners.
The 2WD has no front diff, so you have plenty of room for 2.5" pipes back to mufflers. Since you have a low cost system now, figure in the small headers available, and then have cat pipes made with 2.5" pipe, leading to two 2.5" mufflers. You can turn the outlets down there to make it louder, but lots of mufflers are already loud. So pick your favorite mufflers by sound, trying to find two that are relatively thin to fit them top/bottom together, side to side etc.
There is muffler space for about 9" high and two feet long, typical width for any mufflers. I like the Cherry Bomb Vortex because they are relatively thin and flat, they easily stack and fit without hanging low.
Larger pipe outlets usually are louder and deeper, so a 2.5" tips or bigger will get you the louder sound. Fitting two tailpipes is a whole different deal though, I suggest ending the muffler outlets to the side or just ahead of the rear diff, but one will easily fit on the right side. I'm going to make one fit on the left also, still to figure out, I've seen one done just barely going below/around the spare tire left side. But any shop is going to talk you out of that, or say no, or charge you too much.
Better exhaust manifolds and bigger cat pipes(one pair only), plus two mufflers, will make you happy. It might then require new PCM tuning, which should be a step you want in the near future anyway.
