I went with the Walker/Dynomax 39434 x-pipe, midpipes, and two M/T GT mufflers for my 2008 V-6.
If I had it to do over again, I probably wouldn't. Other than it was too expensive (mostly because of the stainless band clamps and a set of four proprietary muffler brackets), it's also obnoxiously loud and has significant drone. I ended up insulating the trunk and under the rear seats, and now it's more or less tolerable inside but still obnoxious and not neighbor-friendly outside. The A/T GT mufflers are probably a better choice, for the same reason Ford put them on the automatic GTs.
The other problem is a really bad vibration at idle, in gear with the A/C on. I've tried everything I could think of, including checking every exhaust component for clearance/rubbing, and replacing both motor mounts. No change.
Anyone with a V-6 and duals experience this issue? If so, were you able to resolve it?