Tom, it's a hard call... now just how close to factory are you going? Are you wanting it to look just like factory, or to look like a good clean dual system that would like right to most who would ever see it?

Factory would be something like 2.25" from the manifolds, tuck up under the X-Pan (for the vert) and into two resonators, then up and over into a dual in/out transverse muffler, and dual exhaust pipes out the back.

If your going for something that will look right or period correct, but not 100% factory, then I would look into the total cost and time on both systems (local shop and Mail order) and from there, you'll have to make sure the local shop can do the work the way "you" want it to look.

Most good local shops (read independant shops) will have the experience and know how to give you a better fit and finish than a mail order (more generic) system. I found a good shop near me that I will have do one or two more of our cars before I have them extend the Firebirds pipes all the way out the back (turn downs before the axle now)

It may cost a little more in the end, but the work will be solid, and probably fit better, and look nice and clean (welds instead of clamps etc...)

So let us know what you decide, and maybe some pix of the end results?

Good luck - Brett - 67 Drop Top 455!