If you have the tools and (access to a lift would be ideal) but a jack and some jack stands will work just fine (Depending on where you placed the jack stands, front or rear, be sure to chalk the tires and have the car in park with the E-brake on) I would do it yourself, no greater satisfaction than knowing you did it yourself and knowing it's done RIGHT!
I've never done a V6 exhaust before, but have done my 92 5.0 and my 06 GT's exhaust myself (by myself and on the ground with just jack stands) and its a piece of cake, getting to the manifold bolts can be tight squeeze (a drop light, a ratchet with a long extension and a deep dish socket will be your best friends for getting to them) a can of spray lubricant to spray the studs on the manifolds will pay dividends as well, other than that it should be a really easy install.
If you do it yourself just be sure to start the car and crawl back under the car to check for exhaust leaks before taking the car off the jack stands and going for a ride.
Take your time and if you can get a buddy to help out you should be able to do it in under 2-3 hours

If you have any wrench turning experience it might even be possible to do it in like an hour and a half.
Best of luck
One question, when changing out to a dual exhaust setup on a V6, will the car need to be tuned??